Re: [SLUG] Bi-directional rsync?
Are you forced to use rsync? If not you can use csync2 which I think would do the trick for you. On 14 May 2013 09:16, DaZZa dazzagi...@gmail.com wrote: Learned ones! To overcome some crappy web design (two servers, load balanced, no shared storage), I need to implement rsync to synchronise a directory between two servers. Trouble is, it's got to be a two way sync. I.E. File uploaded to web server 1 (don't ask - I told you it was crap web design) needs to be available to download from web server 2 if necessary for future sessions - I.E. I've got to copy the file from server 1 to server 2 in short order (sub 5 minutes). I've ALSO got to do the same from server 2 back to server 1 - so if the incoming upload goes to server 2, it's got to be copied back to server 1. Currently, I've got rsync running on both servers every 5 minutes and synchronising files from 1 to 2, and from 2 to 1. I'd like to just do this in once process - run rsync on server 1, have it connect to server 2 and pull/push all files until the directories match. I don't know if this is even possible with rsync - and if so, I don't know the options required to make it work. The current command being used is rsync -v -rlt directories Can anyone suggest a better option set which could make this a two way sync by just running on the one server? Thanks. DaZZa -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] sorry, you must have a tty to run sudo
On 22 June 2012 09:14, li...@sbt.net.au wrote:
how do I modify so I only pass directory names, NOT file names in $j
thanks for any pointers
*1-
#!/bin/bash
case $# in
1)
DOMAIN=$1
;;
*)
echo Usage: $0 domain.name 12
echo this archives $1 Maildirs
echo all mail over 45 days is gzipped
exit
;;
esac
if [ -s /var/mail/vhosts/$1 ] ; then
cd /var/mail/vhosts/$1
for j in *@*
do
sudo -u#5000 /usr/local/bin/archivemail -d45 $j
done
exit
fi
This should work
for j in $(ls -d /var/mail/vhosts/$1/); do
do_things_with $j (or use ${j%%/} if you don't want the last '/')
done
If you need to check if something is a dir, you can also do
[[ -d /var/mail/vhosts/$1 ]] echo It's a dir!
echo no such domain $i
exit
-
--
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Re: [SLUG] Open source log analyser tools (or: Alternatives to Splunk)
Hi, It really depends on what are your needs. I don't know much about the fancy things from splunk, but you can do some cool things with logstash. There is also a nice ui for logstash, kibana ( https://github.com/rashidkpc/Kibana) On 9 May 2012 17:04, Mark Walkom markwal...@gmail.com wrote: We're looking at 2G a day, which is AUS$30K a year. And were on the S end of SME so it's a hell of a lot. The only way we could cut this amount down would be is if we wrote a customer parser that read the application logs that cut out all the replicated crap (mostly environment variable stuff) and spat out the logs to a separate dir for splunk to read. But then we need to deal with extra storage requirements. Again, when you are a small operation with a small budget, money rules. -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Open source log analyser tools (or: Alternatives to Splunk)
With logstash you have an agent in each server. There you can configure inputs, filters and outputs. Inputs: file, syslog, etc Filters: grep, regexp. Here you can do magic. Outputs: file, elasticsearch, redis, amqp, etc (lots of possibilities) Check the docs to see if there is any filter/output that works for you. I reckon you can do what you need with logstash. But you can probably do the same with some scripts. On May 9, 2012 5:26 PM, Mark Walkom markwal...@gmail.com wrote: -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Wiki software
gitit.net also looks very good. I'm using mediawiki myself, but I'll probably try gitit. El 21 de novembre de 2011 9:17, onlyjob only...@gmail.com ha escrit: My favourite are dokuwiki (PHP) and ikiwiki (Perl). Both do not use DB backend. Ikiwiki rely on git with some of its functionaly, like another interesting one - git-wiki (Ruby). I'm sure you know about wikimatrix.org web site where you can find heaps of information about many wiki. However at the moment I can't open this useful site :( Good luck - please let us know about you choice when you make it. Regards, Dmitry. 2011/11/21 Marghanita da Cruz marghan...@ramin.com.au: Any opinions on the good, bad, ugly Wiki software? I'm playing with PHPwiki (because it is tiny). Marghanita -- Marghanita da Cruz http://ramin.com.au Tel: 0414-869202 -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] dyndns address to CNAME ?
On Mon, Aug 8, 2011 at 19:03, Voytek Eymont li...@sbt.net.au wrote: dumb DNS Q: what's a way to have a dyndns name mapped to a host within own domain.tld ? Either pay them for their custom domain support, or have your domain expose a CNAME that points to their dynamic name. can I map a dyndns host to a CNAME as a hostname on mydomain.tld ? CNAME is like a symbolic link, and it works the other way around: you point to the dyndns host from the CNAME on your own domain. so, I have a machine at home with not-fixed ip, on dyndns, as 'myhomepc.dyndns.com' if I set a bind record as: myhomepc CNAME myhomepc.dyndns.com. to have myhomepc.mydomain.tld that works, BUT, will that work once ip changes, will that propagate to my CNAME...? So, again, symlink: the way that a name is resolved is that when you hit a CNAME you read the target of it, and then go ahead and start the process from scratch with the new one. So, the end user system pretends that they typed in myhomepc.dnydns.com. instead of myhomepc.your.domain. and all. Make sense? Any IP changes matter only for the target name, and the CNAME is more or less unrelated. Daniel -- ♲ Made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Log for timed out SSH connections
On Sun, Mar 20, 2011 at 21:41, Simon Males s...@sime.net.au wrote: We have just switched Internet connections (from ADSL2 to [SH/B]DSL) and I'm finding that SSH connections to the Internet are timing out. I bet whatever device is doing NAT or firewalling on the outside of your network is dropping the idle connection; turning on TCP or protocol level keep-alive messages in SSH will probably solve your problem. Normally SSH sessions could be open all day. I've logged a fault with the provider and they are looking into it. Odds are, if they control the firewall, they will be unwilling to fix this on their end. Not that I am bitter or anything. I'm wondering if I can get some timings from SSH to look for any patterns. Though a timed out session and a nicely exited one look all the same in auth.log I would grab a tcpdump on both ends of a session that fails, and determine what is being seen by both ends. That should conclusively prove or deny my thesis. Daniel -- ⎋ Puppet Labs Developer – http://puppetlabs.com ✉ Daniel Pittman dan...@rimspace.net ✆ Contact me via gtalk, email, or phone: +1 (503) 893-2285 ♲ Made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Which Virtualisation, and why?
On Wed, Jan 12, 2011 at 16:11, onlyjob only...@gmail.com wrote: Regarding virtual loopback it seems that in standard builds of VServer-enabled 2.6.32 kernels available from Debian repositories this problem do not exist. I'm not too sure though but I don't remember experiencing it. It was definitely there is the stable releases of Debian before Lenny, when they presumably decided the experimental VServer patches were sufficiently stable or whatever. Anyway, nice they have solved it. :) Besides it is possible to change localhost address in /etc/hosts ...but not to remap 127.0.0.1, or easily create another interface named lo, or bind to 0.0.0.0, all of which a surprisingly large number of packages assumed would always be present and operational in Debian (and, for which, Ubuntu is generally worse. :) Absence of network virtualization in VServer is deliberate and for a good reason. I can't find much useful information on this on their website about why, but wikipedia claims that this is based on isolation rather than virtualization to avoid overhead, which seems relatively bogus to me given the in-kernel network namespace support is pretty much directly isolation based. Do you know of a good source of information on the VServer side? I am curious to know what the technical differences are (and if that is, indeed, the correct argument from their side) so I can better understand what the trade-off here might atually be. [...] I don't see how kernel support relevant to RHEL upstream - a year ago there was no OpenVZ support for 2.6.32 whatsoever. And frankly this was one of the reasons I've chosen VServer for a machine hosting around 20 VMs. ...er, OK. So, the use of the RHEL kernel is relevant because RedHat invest substantially in stabilizing the kernel and backporting newer drivers to it. This means that unlike the Linus 2.6.18 kernel (for example) you can get support for modern Intel NICs and other controllers, so it doesn't suffer nearly the trouble running on modern hardware that the version number might suggest. Given that, in many cases, security and driver support are the primary motivators for using a newer kernel this can, indeed, help with (though not universally solve) the issue that the OpenVZ kernel version lags the upstream kernel version available in distributions. Obviously 2.6.32 have a number of important features notably KSM which makes a lot of sense for virtual host and also EXT4. Er, as of 2.6.36 the KSM feature still scans only memory specifically registered to it by the application. So far as I can see the VServer patches don't do anything special to mark memory as possible to share for code running in them, and pretty much nothing other than KVM/qemu does out in user-space, so I wouldn't have thought that KSM made much difference. As to ext4 ... *shrug* I think that is a religious debate that would distract from the real discussion at hand; I regard anyone running ext4 on a production system as vaguely strange since it is still so young and experimental compared to more tested code but, obviously, you don't share that reluctance to move. :) [...] *more performant: I agree with you that difference in network performance between VServer and OpenVZ is not terribly different. Perhaps it can be manifested with some sort of artificial testing. However here I was quoting Herbert Poetzl (VServer developer). While performance difference is not too big there is another thing which I believe is equally important - simplicity. If the same result can be achieved easier, without even little virtualization overhead it is certainly better, more maintainable, probably has less bugs etc. Simplicity matters. *nod* Part of my view on the subject is that VServer made some bad technical decisions that kept their kernel code simple in exchange for adding a huge amount of complexity to every container; part of that (lo virtualization) they have obviously decided can be corrected these days. So, I agree, but I think that whole system complexity is a much more important metric than just kernel complexity. (OTOH, I also think that a bunch of the OpenVZ bits – like UBC – are disasters of complexity and I am very glad they will not make it in to the mainline kernel. :) Anyway, thanks for sharing your experiences and discussing this. I like to talk through these issues so I can better understand where things stand – and I already learned some useful stuff I didn't know from you. :) Regards, Daniel -- ✉ Daniel Pittman dan...@rimspace.net ⌨ dan...@rimspace.net (XMPP) ☎ +1 503 893 2285 ♻ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Which Virtualisation, and why?
On Wed, Jan 12, 2011 at 20:10, dave b db.pub.m...@gmail.com wrote: Also has anyone looked at LXC :P ? In my previous job, where we did the other bits, we did some testing on developer systems; our conclusion was that LXC was at least a couple of years from being useful in the real world based on a pretty much endless collection of shortfalls and bugs in testing. My very strong hope is that it will stabilise and one of the implementations built on the kernel tools (because the libvirt LXC and plain LXC projects are entirely different user-space code) will become the standard for doing this inside Linux. Having run identical kvm guests, I found that KSM actually wasn't that much of a benefit as a 'cpu user' (while it doesn't seem to use much ... potentially the cpu could down clock to save power instead of running KSM). We never saw much benefit, and were pretty happy that we got better memory use overall from OpenVZ containers rather than KVM machines even where they were identical. Regards, Daniel -- ✉ Daniel Pittman dan...@rimspace.net ⌨ dan...@rimspace.net (XMPP) ☎ +1 503 893 2285 ♻ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Which Virtualisation, and why?
On Tue, Jan 11, 2011 at 16:24, onlyjob only...@gmail.com wrote: No, no, please not OpenVZ. It is certainly not for beginners. Better use VServer instead. I used both, first OpenVZ (but was never really happy with it) and then VServer. Have VServer added network virtualization yet? Last time I used it they hadn't, so your containers didn't have, for example, the loopback interface, or a 127.0.0.1 address they could use. That made for a constant, ongoing pain in the neck compared to OpenVZ which *did* look like that. Every single distribution package that assumed, for example, that it could talk to 'localhost' would do the wrong thing. Ah. I see the experimental releases do add support for a virtualized loopback adapter, along with IPv6, which is nice, and probably addresses my biggest operational issue with VServer. There are number of benefits of VServer over OpenVZ: * GPL License http://openvz.org/documentation/licenses The OpenVZ software — the kernel and and the user-level tools — is licensed under GNU GPL version 2. It is also notable that a bunch of the upstream, in-kernel code *is* from OpenVZ, including a bunch of the namespace support that underpins the LXC implementations and, these days, OpenVZ itself. Can you tell me where you got the impression that OpenVZ was not GPL? * Better kernel support: OpenVZ kernel 2.6.32 become available only recently. VServer supported 2.6.32 for a while - much much longer. OpenVZ's adoption of new kernels is quite slow - perhaps just too slow... FWIW, because their upstream kernel is based on the RHEL kernel releases, we often found that they had sufficiently recent drivers despite the older core version. This is a genuine drawback, however, and makes it hard to have upstream support if you are not using RHEL as your base system (eg: Debian, Ubuntu.) Er, also, am I looking at the right place? I went to check out the feature equivalent stuff because I am quite interested in keeping up, and the linux-vserver site tells me that the latest stable release is vs2.2.0.7 for 2.6.22.19 – they have an *experimental* patch for 2.6.32, but I presume there must be some other stable release for the .32 series or something? [...] * more performant: Linux-VServer has no measureable overhead for network isolation and allows the full performance (OpenVZ report 1-3% overhead, not verified) Our measurements show pretty much identical performance cost for either tool, FWIW, and we generally found that either of them was able to exhaust the IOPS or memory capacity of a modern server well before they could make a couple of percent of CPU overhead matter. (KVM-like tools were far worse for this, of course, because of their increased IO and memory overheads.) [...] * Easier. I don't agree here: other than the more modern set of front ends (like Proxmox) for OpenVZ, I never found there to be a detectable difference in tools overheads between VServer and OpenVZ, and OpenVZ was actually a bit easier to fiddle with outside the rules and all. Regards, Daniel -- ✉ Daniel Pittman dan...@rimspace.net ⌨ dan...@rimspace.net (XMPP) ☎ +1 503 893 2285 ♻ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Upgrading OS RAID
On Sun, Jan 9, 2011 at 14:05, Kyle k...@attitia.com wrote: it appears one of the disks in my s'ware RAID is failing. So I've come to SLUG for some consensus and confirmation. 1. How do I go about rebuilding the RAID with ALL brand new disks (obviously no longer the same disks, but now newer spec larger disks) such that I don't lose not only the data but don't have to rebuild the whole machine again? Replace the disks one at a time, allowing the rebuild to fully complete between each disk. Once you have the entire array running on the larger disks, mdadm can increase the size of the array, and you can resize your file system inside it. (...and check you *can* do that before you go to the trouble.) My advice is to read the mdadm manual page to find out how; if that doesn't make sense, don't tackle this replacement yet, but keep learning until it does make sense - because a slip here can cost you all your data. It is highly advisable to have good backups, though, while doing this. The most likely time to discover that you have a bad block on a second disk is during a rebuild, and that could result in the array going away. This is not unrecoverable, but it is hard. :) Obviously, create a new array and copy data works too, and isn't a bad choice if you can manage it. Practical issues like space in the case might make it hard though. 2. I'm better sticking with linux s'ware RAID rather than setting up a m'board BIOS supported RAID aren't I? Absolutely. Unless you have a real hardware RAID card, use Linux software RAID. Even then it isn't a bad choice. :) The built-in stuff on your motherboard isn't hardware RAID, but software RAID with a bit of BIOS glue to support booting from it. 3. It's been a while since I delved into h'ware etc. So SATA II disks will simply plug into, and function correctly, SATA plugs, yes or no? Or are we now at a stage where I also have to worry about whether or not the m'board will actually support the disks I want to put in? Yeah, it should be just fine. Regards, Daniel -- ✉ Daniel Pittman dan...@rimspace.net ⌨ dan...@rimspace.net (XMPP) ☎ +1 503 893 2285 ♻ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] website questionnaire software?
On Thu, Jan 6, 2011 at 19:40, Sonia Hamilton so...@snowfrog.net wrote: Can anyone recommend software for setting up website questionnaires? Google Docs. Seriously, their form stuff is pretty reasonable, and gives a spreadsheet - which is often how folks actually want that data in the end.. Otherwise, SurveyMonkey and few other services will do an OK job of presenting this. Regards, Daniel -- ✉ Daniel Pittman dan...@rimspace.net ⌨ dan...@rimspace.net (XMPP) ☎ +1 503 893 2285 ♻ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] DD images and checksums
On Thu, Dec 23, 2010 at 13:07, Robert W robertw...@gmail.com wrote: I've searched the Ubuntu forums for an answer and couldn't find one, so I figured I'd ask here instead. If I use DD to back up my USB drive to a file, should I expect the checksum of the image file created to be the same as the checksum produced by the device (for instance, /dev/sdb)? I've been getting different checksums and I wanted to know if it was because of an error writing the image file, or because of something else. Assuming that you are not *using* the USB device at the time, you should get the same values; I often use that to verify that a copy of a disc is correct. Regards, Daniel -- ✣ Daniel Pittman ✉ dan...@rimspace.net ☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Converting a Hard Drive to a Virtual Machine
david da...@kenpro.com.au writes: I have an Ubuntu box running which I would like to be able to clone into a virtualbox VM. I don't want to shut the hardware down, or play with it too much because it's a live server. Is it possible to use MondoRescue or some other software to clone the server hard drive, preferably without shutting it down, and then create a virtual machine from the resulting image? Not robustly, for cloning the raw disk, because you will end up with a really messed up file system. If you could stop file system access for a few hours it would work, but that has ... probably the same issue. :) What you *could* do is boot a LiveCD in the VM, and use rsync or something to clone the files into the new machine. Then, you can keep the block level consistent and only risk file level oddities, which are much less nasty. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
XecureBrowser - looks like snake oil to me. (was Re: [SLUG] Browsers for banking)
Mada R Perdhana mrp@gmail.com writes: How interesting. It looks pretty much like snake-oil, a scam intended to scare folks who don't know much about security, to me. The problems start with their lack of presence: the main bits of presence are a FaceBook page, a twitter account, and a Yahoo Group with barely coherent writing about their content. They do, though, do the scam-focused thing: waffle vaguely about security issues, claim (but not prove) they are more secure, then tell you that you are a bad person if you don't instantly convince your friends to use their software. They do have an email address, apparently attached to some Google Apps hosting, and a website with links to their 2008 security forum, and a copy of the same information about security (eg: none) as their FaceBook page provides. They start with the *technical* issues by claiming that techniques of cracking the SSL implementation are widespread, but provide no evidence about what those techniques are - or why they are, for example, not being widely reported since that would be huge security news. If we generously assume that they mean that attackers are running software on your machine to intercept content *without* having to violate the cryptographic security of the SSL/TLS protocol then they have a huge burden of proof in the form of demonstrating their software actually does anything. Which, of course, they don't deliver. Meanwhile, if we look to their writing on the facebook page they have some excellent advice for you: you can keep the software safe by keeping the original zip file around, and if you ever have a doubt (sic) you can just extract the executable again. Because, y'know, an attacker would never, ever think of being able to attack a bit of software every time it ran, or to fiddle with an executable inside a zip file. That would be, y'know, hard! They also explain that in the next couple of versions they will be working to fix security problems like hijacking of your laptop - so, y'know, if this issue has not been addressed in this version then, hey, apparently our generous assumption earlier was inaccurate. They *can't* be claiming that they secure the system against local attacks, leaving *only* that these hackers are breaking the SSL/TLS protocol. Oh, well... Their public don't help, either. The top hits contain claims like this: As you know, break-ins money can through hypnosis, ATM card fraud, and phishing. Phishing is a cunning technique to obtain sensitive information while transacting through Internet Banking. They stole your information such as the username, password, credit card numbers and so on-depending on the form of phising I know that one of my huge security concerns, which a secure web browser could help with, is that I might be subject to hypnosis or ATM card fraud! Those damn hackers and their hypnotic virus powers! So, MRP: this looks convincingly like something that is at best snake-oil, and at worst outright fraud. Care to respond? Daniel Try XecureBrowser, it's a browser design for ibank transaction, protect from ssl injection or anything which relate with ibank crime type. regards, mrp On 11/10/10, Jeremy Visser jer...@visser.name wrote: Jim Donovan said: Commonwealth opens extra windows but only logs off in one of them; you have to close the others by hand. Not that they will work after logoff but it's lousy security. I don't know what browser you use, but in Chromium I just typed 'netbank.com.au', logged in, and not a single browser window was opened. The NetBank interface just opened in the same browser window. -- Linkedin : http://id.linkedin.com/in/mrpbpp PGP ID : 0xDC3A483A PGP Fingerprint : FCBE 697C 3C47 89D2 C28F 6C94 E607 7E99 DC3A 483A See http://www.keyserver.net or any PGP keyserver for public key Never Trust an Operating System You don't have the Source for... Closed Source for device Driver are ILLEGAL and not Ethical... act! Isn't it, MS Windows a real multitasking OS?, Why? 'Cause It can boot and crash simultaneously! -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Re: XecureBrowser - looks like snake oil to me.
Voytek Eymont li...@sbt.net.au writes: On Thu, November 11, 2010 11:38 am, Daniel Pittman wrote: It almost sounds like you are trying to disagree with me here, which seems strange, given that the issue in the article was that it turns out people with low levels of technical experience are vulnerable to social manipulation. I can't quite tell if you are disagreeing or not, though, which is strange. :) agree with you, and, appreciate your concise summary of the XecureBrowser, likewise, I followed up the XecureBrowser link. yes, that's what I meant, here's another example Ah. Sorry for the confusion, then. :) sorry for not making it more obvious. I don't know I would, personally, assume that it was your side that slipped here. I am happy to say that this is not my most ... focused of days. ;) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
[SLUG] Re: XecureBrowser - looks like snake oil to me.
Mada R Perdhana mrp@gmail.com writes: I think, it is too careless if this is just a scam, because the developers also threw a request to the public (the information security community) to perform tests on their application. This is a pretty certain sign of ... well, not a scam, but a sign that this is snake oil - something that doesn't really do what it claims. The most important this is a sign of that is that it is an effort to prove that something is secure by demanding other people take the trouble to prove it is *not* secure. Which fails disastrously: if no one in the security community actually bothers to test it, is it secure, or just untested? It also fails disastrously because it proves that a set of people, if they actually bother, can't break it. That proves *nothing* about the ability of other folks to do so. This /sounds/ like proof of security, but isn't (even if done as intended), which is a classic sign of snake oil. from existing web (https://www.xecureit.com/xb/), we could also seen that they had an affiliation with ISACA and CISSP certification, which in my personal opinion it is to reckless to drag this two bid name into, since it would make a big reaction from the information security communities. No, there wouldn't, for several reasons. The most important one is that offering CISSP training has nothing at all to do with the secure browser they are offering, and they make absolutely no claim that it is connected. The second, and pretty much equally important reason, is that the information security community doesn't really give a damn about a fight between Cisco and some tiny little company over the inappropriate use of a Cisco certification. Now, you might make an argument that they were trying to conflate the presence of those things with any sort of actual security of the product - which would be supporting evidence that they were selling snake oil, not evidence against. May be some of security experts in here could also do some test with that thing, to prove whether ,xb just a scam or it is really works to secure ib transaction. Why on earth would I spend my time trying to prove something like that, rather than just recommend things that are known and understood to work? You seem to be assuming that the burden of proof is on the Internet security community to prove that this is a bad thing. That isn't really how actual security stuff works: there, the burden of proof is on the claimant. If you want us to believe that XB is worth something, prove it. Show the proof that it actually, measurably improves user security. anyway, again.. everything returns to the user, to determine which are the most secure (or convenience?) way to conduct an ib transactions. Are you trying to argue that popularity is a good way to identify the security of a product? Didn't FireSheep show us that was ... hard to support? (Not to mention that we have decades of other proof that security is not a pressing concern for users, but whatever. :) ...and, frankly, that claim only serves to convince me that the term you want is sucker, not user, here: the audience are people who are convinced that there is some secret security sauce in the product without actually understanding anything about why it might make them more secure. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] chroot - landing/ cd'ing into home dir?
Zenaan Harkness z...@freedbms.net writes: This has stumped me for a few days now. When I chroot into my chroot dir, I am always started at the / (root) directory. Uh-huh. Just this morning I re-read the bash man page, and finally inserted cd $HOME at the start of /etc/profile. That may surprise various (poorly written) scripts out in the wild which make assumptions about where they start; putting it in the per-user script would have likely been a better choice. Is there a more elegant way? Not really, not. Eg, should I be trying to run /bin/login or something instead of bash? It wouldn't hurt, I guess, but in essence the chroot thing assumes you know what you mean to do, so unless the contained code DTRT you get this default location. There isn't any more blessed or correct way to do what you want inside the chroot. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Is Windows XP much faster under hardware virtualization?
Jeremy Visser jer...@visser.name writes: Jon Jermey said: I'm currently running Windows XP for work in VirtualBox under Mint, and it is usable but sluggish. I'm in the market for a new PC and one of the options is to get one with hardware-assisted virtualization. Can anyone comment from personal experience on whether this will make a) a spectacular difference; b) a moderate difference; c) no difference at all to the speed of virtualized XP? From personal experience, I can say that cannot notice any (perceptible) performance difference whatsoever in VirtualBox whether hardware virtualisation is turned on or off. None at all. Almost no one will - the performance difference is real, but mostly shows up in memory bandwidth, page-mapping performance, and context switching performance. That means you need to be doing something that pushes one of those to the limit *without* hitting other limitations of the VM to actually see any change. [...] Are there different types or levels of hardware virtualization available off the shelf, or it is one-size-fits-all? Well there’s Intel VT-x and there’s AMD-V, which are the duopoly’s equivalents. Both are supported by VirtualBox, VMware, KVM, etc. Personally, I think that if you buy a new PC with hardware virtualisation, the performance benefit you will see will be coming from the faster hardware more than the VT-x/AMD-V support. *nod* Also, keep in mind that one of the biggest factors in VM performance is going to be I/O for most users. That means that the performance of your paravirtualized devices is the key for getting better performance - and that usually just means picking a VM solution with appropriate guest drivers and all. (Unless you plan on mapping physical hardware into the VM, in which case VT-d or the AMD equivalent makes a difference.) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Is Windows XP much faster under hardware virtualization?
justin randell justin.rand...@gmail.com writes: On 1 November 2010 09:16, Daniel Pittman dan...@rimspace.net wrote: Are there different types or levels of hardware virtualization available off the shelf, or it is one-size-fits-all? Well there’s Intel VT-x and there’s AMD-V, which are the duopoly’s equivalents. Both are supported by VirtualBox, VMware, KVM, etc. Personally, I think that if you buy a new PC with hardware virtualisation, the performance benefit you will see will be coming from the faster hardware more than the VT-x/AMD-V support. *nod* Also, keep in mind that one of the biggest factors in VM performance is going to be I/O for most users. That means that the performance of your paravirtualized devices is the key for getting better performance - and that usually just means picking a VM solution with appropriate guest drivers and all. (Unless you plan on mapping physical hardware into the VM, in which case VT-d or the AMD equivalent makes a difference.) yep, I/O is normally a killer. at work, all dev machines have (at least) two physical drives, so VMs can be given a disc separate from the host OS. we find that's the simplest, best bang-for-buck way to get good VM performance. Only if you have PV disk drivers - performance with the emulated hardware, even SAS and SCSI controllers, is generally way lower than the PV stuff because of the overheads of emulation.[1] FWIW, using KVM we reproduced the widely reported native performance using direct I/O and an LVM slice results; those later should work for any raw block device, not just LVM. (Which matches your comment, of course. :) Daniel Footnotes: [1] Really good non-PV drivers and good hardware can reduce it to the equivalent of only a few transitions into kernel mode, but they can't be as efficient as the one or less that PV drivers manage. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] An apt-get question.
wbenn...@turing.une.edu.au writes: I don't understand this. I have the original download file from Freshmeat on my desktop. The file is CptCrosswords-1.2.Linix.x86.tgz [...] [I know I know. I can probably use this, but I'd still like to know which memory hole the .tgz file fell in.] At a guess your web browser and/or their web server colluded to notice that it was compressed, and to automagically decompress the gzip bit for you, with only the tar part left behind. (My next guess is that your web browser hates you deeply, and removed the gz extension without decompressing it. :) I intend to use ./configure make make makeinstall Will the fact that its a tarball make any difference, or will I have to de-tar it first? Well, you need to extract the files from the tar archive, yes. Perhaps this will be made clearer with a little explanation, and please forgive me if this is obvious to you: A tar file is a single stream of bytes that holds a whole lot of files and their metadata (permissions, directory, etc), one after another. Unlike the zip format and other things popular on non-Unix platforms this is just the files - no compression or anything. To compress these for transmission most Unix folks use a compression filter, which takes one stream of bytes (the tar file) and outputs another (the compressed tar file). gzip and bzip2 are popular here. So, a 'tgz', or 'tar.gz', file means: A set of files ... ...wrapped into a single stream using tar... ...fed through the 'gzip' compression filter... ...and handed to you. So, if something removed the gz part and left only the tar part you still need to unpack the tar bits. (In 'tar xfz foo.tar.gz' the 'x' means extract, the 'f' means from a file, and the 'z' means decompress the gzip part. Omit that, for only 'xf', and you will unpack a tar file that is not compressed.) Regards, Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] debmirror: gpgv not finding debian key
Zenaan Harkness z...@freedbms.net writes: I had this working 3 weeks or so ago, but can't figure out what's gone wrong. At a guess the key changed; I know they were rotating the Debian archive keys, though I thought it was going to be longer... [...] # cd $GNUPGHOME ls -l total 76 -rw--- 1 justa justa 5735 2010-10-15 16:47 pubring.gpg -rw--- 1 justa justa 5735 2010-10-15 16:47 pubring.gpg~ -rw--- 1 justa justa 0 2009-10-19 18:46 secring.gpg -rw--- 1 justa justa 1200 2010-10-15 16:47 trustdb.gpg -rw--- 1 justa justa 23690 2009-10-19 18:52 trustedkeys.gpg -rw--- 1 justa justa 23690 2009-10-19 18:52 trustedkeys.gpg~ apt and friends use a private keyring; use apt-key to maintain it. If you import that key into the apt-key store your problem should be resolved. Regards, Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] On buying a laptop.
Tony \H.G\ Candito blindra...@gmail.com writes: On Thu, Oct 14, 2010 at 2:44 PM, Luke Yelavich them...@themuso.com wrote: On Thu, Oct 14, 2010 at 02:41:39PM EST, Luke Yelavich wrote: Coming from a point of view of audio stack maintainer in a distro, I'd say stay away from Toshiba. There have been many issues surrounding hda audio and Linux in the past few years that myself and colleagues have tried to help sort out. I also believe the kernel maintainers for Ubuntu also recommend users stay away from Toshiba. I can't give any more information than that, but I personally trust the kernel maintenance team of Ubuntu when they suggest that people look at other manufacturers. I should add, that such audio issues were hard to diagnose, due to some ACPI oddities. I could dig for the bug refs if people are really interested. OK, so now that we've learn't what isn't safe. What is? ThinkPad, mostly. Their very bottom end stuff is really IdeaPad inside, which is not the same quality as the ThinkPad hardware. See http://www.thinkwiki.org/ for details on what does or doesn't suck. Apple, after six months. Not because of OS-X, mind you: because there are about two dozen types of mac hardware *total*, compared to however many thousands of combinations of non-mac laptop hardware, you can be pretty confident that it will all be fairly rapidly supported, and solid once it is. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] On buying a laptop.
wbenn...@turing.une.edu.au writes: So, I wish to buy a laptop. Choice suggests the Toshiba Satellite LP500. I recall some time ago a discussion on whether the AMD processors were better at Linux than those of Intel. As I also recall, majority opinion was that there was 0 in it. Is this still the case? They are pretty much indifferent, other than the basic performance stuff that any benchmark highlighting CPU performance will show you.[1] Has anyone had experience (+ or -} with the Toshiba that's worth airing? Their warranty support was a PITA when I had to deal with them. If that matters to you, another vendor might be a better choice ... but the only vendors I have dealt with who didn't suck were IBM (ThinkPad, and Lenovo have been much more ... mixed), and Apple. Other folks I know say Dell service was good, though my experience wasn't. Daniel Footnotes: [1] That is: don't just compare the speed, compare the performance. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Greylisting Sendmail
Nigel Allen d...@edrs.com.au writes: Customer of mine currently has their own in-house mail server. Machine runs CentOS 4.8 with Sendmail, spamassassin and mimedefang. RBL's are covered in sendmail.mc with spamhaus and SORBS. Can anyone think of any reason why this combination would not play nice if they also implement greylisting? Nope. Any gotchas anyone is aware of? Some providers, typically big ones (*cough* Telstra, Optus) tend to play poorly with greylisting: they have a separate pool of senders if the first attempt is not accepted, and can delay up to 24 hours before sending.[1] Some greylisting tools have a set of exceptions for dealing with this, others don't. The later ... hurt more. :) Daniel Footnotes: [1] Well, could, when last I managed a system with greylisting, about nine months ago. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: Subject: [SLUG] change to linux and google chrome
Martin Visser martinvisse...@gmail.com writes: On Sat, Oct 9, 2010 at 6:30 PM, Brett Mahar brett.ma...@gmail.com wrote: You might like to check out SW Iron instead of Chrome, it is the same thing but without the many Google tracking devices built-in: http://www.srware.net/en/software_srware_iron_chrome_vs_iron.php You just gotta love that SRware are obviously down on Google tracking yet are quite willing to take their money by offering Google Ads on both the side and bottom of their page. Yeah. FWIW, once you start to poke at that the whole thing ... aw, heck. Let me just add to this an excerpt from the Debian mailing lists when this same thing came up: http://forums.debian.net/viewtopic.php?f=20t=50358 At the time SRWare also used a service provider that used pop-under advertising to make money. So, yeah. As far as I can see this is, in essence, an implementation of the principal that if you pander to paranoia then you can make money from ... the folks who care enough to worry about privacy, but not enough to actually do the research themselves. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Listing local wifi access points?
Erik de Castro Lopo mle+s...@mega-nerd.com writes: darrin hodges wrote: The aircrack-ng http://www.aircrack-ng.org/ suit contains a utility that will list AP's. Sorry, any program whose getting started tutorial [0] has a first step of Determine the chipset in your wireless card is going in the wrong direction. I have absolutely no interest in cracking other peoples wifi. What I'd like to do if figure out which channel in my local area is the least congested so I can park my AP on that channel. Cool. Don't forget that if you are using 2.4GHz there are *three* channels, no matter what the card says: only 1, 6, and 11 are non-overlapping, so you will get a performance hit from anything that crosses over between them. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Hosting e-mail?
Amos Shapira amos.shap...@gmail.com writes: [...] Could someone suggest a better mail service we can rent separately from web24 and point the MX records for that domain? Fastmail.fm are good, but... just something which will reliably forward e-mail to our various gmail mailboxes. ...would the free Google Apps for Domains meet your needs? It is limited to 50 mailboxes, and is separate from your current gmail account, but should give you equal reliability and capacity. (Plus you are obviously happy with their overall service and all...) Regards, Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Hosting e-mail?
Amos Shapira amos.shap...@gmail.com writes: On 27 September 2010 15:03, Daniel Pittman dan...@rimspace.net wrote: Amos Shapira amos.shap...@gmail.com writes: ...would the free Google Apps for Domains meet your needs? It is limited to 50 mailboxes, and is separate from your current gmail account, but should give you equal reliability and capacity. (Plus you are obviously happy with their overall service and all...) Thanks. Will propose it to her. No worries. My next choice would definitely be fastmail.fm; we recommend and resell them here at work, and I know some of the folks who work for them. They are solid, if all you want is great IMAP mail support. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] copying binaries from one Centos to another?
Voytek Eymont li...@sbt.net.au writes: On Sat, September 18, 2010 3:37 pm, Daniel Pittman wrote: Voytek Eymont li...@sbt.net.au writes: That will not help unless you rebuild Cacti to use the older version of RRDTool. (Also, are you /sure/ it is RRDTool and not something else in the Cacti stack that causes the performance problems? RRDTool is crazy-efficient, so I wouldn't pick it as the first point to suspect. OTOH, if you measured it and found it was the cause then you measured it and all. :) Cacti has a setup screen where path to binaries like rddtool can be entered; That should be sufficient, then, to use your custom version. [...] I thought the issue was again lack of math co-pro, and, will 'go way' on the P4, initially Yeah, and naturally it didn't because there isn't anything Intel make that doesn't have a nicely fast math coprocessor these days (and, in fact, you have to go back to the days of the i486 to get something that didn't ship one on-die and all... :) Cacti was using RRDTool 1.2x, then after a yum update, it got 1.4, I 'fixed' the path in setup, but, a screen draw is painfully slow now, based on what I found on the Celeron system, it seems it's similar issue A screen draw? Are you running X locally on the system, or is this on your client? Neither one necessarily points to RRD 1.2 vs 1.4, although it could be involved in either. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] copying binaries from one Centos to another?
Voytek Eymont li...@sbt.net.au writes: On Sat, September 18, 2010 7:17 pm, Daniel Pittman wrote: Voytek Eymont li...@sbt.net.au writes: A screen draw? Are you running X locally on the system, or is this on your client? Neither one necessarily points to RRD 1.2 vs 1.4, although it could be involved in either. sorry, I meant lag to generate /populate graph images in the browser, to load the cacti graph page in a browser on a client over ethernet OK. So, just to check: can you reproduce this performance problem with a page that contains only one single graph? One of the big performance ... well, not problems any longer, but issues with our use of munin in-house is that the default view for a host contains something like 60 or 80 graphs[1]. Using the CGI or FastCGI drawing model this, by default, means that we fired off something like 120 processes on the machine when we visit that page. That caused some performance delay in getting results, because they all took about the same length of time to draw, and were all CPU hogs... So, it might be worth checking if your problem isn't RRD, but rather the fact that you have lots of instances running concurrently on an old and slow machine[2] that just take ages to start delivering results. Daniel We fixed it my limiting concurrency, so you get less overall delay, and faster initial results, out of the system. Footnotes: [1] We love us some metrics, and how! [2] Heck, with a P4 or Celeron it wasn't a fast machine even back in the day, thanks to Intel's foolish micro-architecture decisions and all. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] copying binaries from one Centos to another?
Voytek Eymont li...@sbt.net.au writes: I have a Centos 5x system with RRDTool 1.2x as in # ls bin include lib share # pwd /usr/local/rrdtool-1.2.27 I want to use this on another Centos 5x, do I need to copy anything else beside recursive /usr/local/rrdtool-1.2.27? Maybe. That setup /looks/ like a complete install of rrdtool under that path, but unless you actually know that there is no assurance it is true. or is it a 'bad idea' to copy from one system? Generally, maybe. Technically, no, it should work fine by and large. You might run into issues having to get older versions of libraries that the binary depends on, and if the glibc versions are far enough apart their could be trouble, but it *should* work. However, outside the strictly technical you are probably inviting even *more* effort and suffering later using a hand-managed version of that package. (I've setup a Centos 5 to run Cacti on Celeron 1.7GHz, but, it seems to really struggle, maxing to 100% (guess it wants arithemetic processor that Celeron doesn't have ?); It sure does. Whatever the problem was, it wasn't that. (Probably just that Cacti needs more CPU than it could get, possibly just in sudden bursts. :) so, I found a P4, and, setup Cacti, that was better, till yum update updated RRDTool from 1.2 to 1.4, now, cacti web page load really lags, hence I thought I'll backgrade to RRDTool 1.2) That will not help unless you rebuild Cacti to use the older version of RRDTool. (Also, are you /sure/ it is RRDTool and not something else in the Cacti stack that causes the performance problems? RRDTool is crazy-efficient, so I wouldn't pick it as the first point to suspect. OTOH, if you measured it and found it was the cause then you measured it and all. :) Regards, Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] monitor IP address
Amos Shapira amos.shap...@gmail.com writes: On 11 September 2010 14:44, james j...@tigger.ws wrote: I've changed ISP to iinet and I now have a dynamic IP. I use a router/adsl modem. Just brainstorming in case I've missed the obvious. I need to monitor my IP given to the router. What do you need it for? Maybe the context will let us give more useful answers. *nod* FWIW, there are two reasons this usually comes up in my experience: the first is general interest, for which I would also recommend whatismyip, or just logging in to the modem and letting it tell you. The second is running services, for which I highly recommend using any one of the dynamic DNS update services that pretty much every ADSL modem has a built-in client for these days. That way the modem can take care of all the hard work for you, and you just sit back and use the DNS name. (Don't run an SMTP server on a dynamic IP, though. It is a really bad and painful way to discover how much lost and misdirected email sucks, since I pretty much promise that the one time you are *depending* on that email getting through your IP changes and someone else with an SMTP server gets the address, then sends back a 5XX to your correspondent.) My first idea is to have the router log remotely, monitor the log, and surely there will be some IP and IP changed info. How about whatismyip.org? (as opposed to .com, which gives a larger and more complex page): I would just script getting it out of the modem, if the dynamic DNS option wasn't satisfactory. Much lower overhead, and zero cost to both you and the International transit links. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Re: fedora 13 qemu guest (Peter Miller) (Daniel Pittman)
Brett Mahar brett.ma...@gmail.com writes: That sounds suspiciously like you are either running fully emulated (eg: no KVM support) on Slackware, or that you don't have virtio on that platform. It would be interesting, to me, to know if either of those guesses were true, because I have a current need to improve my skills diagnosing KVM performance issues and feedback helps with that. :) I only thought it was that because I could not think what else it could be. In the next few weeks I hope to have some time to investigate further, and will let you know. Well, cool. FWIW, checking for virtio should be as simple as lspci inside the guest, and checking if you have a virtio device or not. Is the backing store for the virtual machine also on the USB disk? If so it would point a finger toward guest I/O performance is the pain point, and the introduction of USB would just be making a painful service slower. In all cases the virtual hard drive was on an (real) external usb drive (not the same one as the host OS was sometimes on). So I don't think the guest I/O is the culprit. Yeah, that would eliminate that by ensuring it was identical. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] fedora 13 qemu guest (Peter Miller)
Brett Mahar brett.ma...@gmail.com writes: I'm trying to use qemu to host a Fedora 13 guest. On that note, be aware there are vast differences in the speed of applications running on qemu virtual machines, depending on the host system. Eg, BOINC on Debian or Suse running inside a virtual machine, with an Ubuntu 10.04 host is about 10 times faster than on Slackware 13 host (MIPS measured by BOINC software). That sounds suspiciously like you are either running fully emulated (eg: no KVM support) on Slackware, or that you don't have virtio on that platform. I am guessing this is due to Ubuntu kernel being built with kernel same page merging, and Slackware without, but am not sure. That seems unlikely: other than the cost to scan for pages to merge (which hurts Ubuntu) that would only make a difference if you were pushing the limits of your host memory capacity *and* KSM shared enough to avoid I/O in the guest. It would be interesting, to me, to know if either of those guesses were true, because I have a current need to improve my skills diagnosing KVM performance issues and feedback helps with that. :) Also inexplicably, having the host OS boot from an external usb hard drive causes major drop in the speed of the virtual machine, far beyond what would be caused by disk access times. I am not sure why this happens. Well, it would slow down the host OS some, because USB is a fairly slow and high latency protocol for disk access, but otherwise it shouldn't fundamentally alter the running kernel. Is the backing store for the virtual machine also on the USB disk? If so it would point a finger toward guest I/O performance is the pain point, and the introduction of USB would just be making a painful service slower. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Travelling Overeseas - USB Modems
Rick Phillips r...@greyheads.net writes: I presume some people on this list travel to the UK and Europe. We will be travelling in Europe on a guided tour where the use of free internet in coffee lounges is not an option and my experience of a couple of years ago was that buying Internet time in the hotels where we stayed was horrendously expensive - made worse by the exchange rate. Are USB 3G modems a reasonable alternative? If so, what would members recommend? Buying a service in the country you are wanting to use it in, since no one anywhere has reasonable International data roaming rates. Most countries offer an inexpensive pre-paid SIM that you can slot into an existing 3G / GSM modem and use on their network. If you are travelling to Japan things are harder, but pretty much all of Europe is fine for picking up a pre-paid data SIM without trouble. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] [slightly OT] video upload site with API?
Sonia Hamilton so...@snowfrog.net writes: [slightly OT] Can anyone recommend a video upload site (like Youtube, DailyMotion) that has an easily scriptable API, for uploading a lot of videos, that also allows passwording of the videos? YouTube? [1] OTOH you explicitly asked for this mentioning YouTube so I assume that API can't meet your needs somehow — in which case, how doesn't it work for you? Daniel Footnotes: [1] http://code.google.com/apis/youtube/2.0/developers_guide_protocol_direct_uploading.html#Direct_uploading -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] High I/O file systems
Max Wright maxwrigh...@gmail.com writes: Has anyone implemented any of the high I/O filesystems which have been added to the kernel? Well, we use XFS widely because the performance is enormously better than ext3, and they have worked hard to redress the few metadata heavy workloads that they used to perform poorly at. We have some busy databases which put ext3 under stress, I am wondering about Oracle's fs for instance. That would be a universe more experimental than /I/ would be comfortable with in production at this point in time. (Assuming you mean btrfs rather than luster or one of their other cluster file systems. ;) Regards, Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] flashing motherboard with no floppy drive
Martin Visser martinvisse...@gmail.com writes: It looks like according to this all you need to make sure is that a barebones DOS session is running. According to this, http://www.pcstats.com/articleview.cfm?articleid=1605page=4 , if you boot a DRDOS CD that should work. These days FreeDOS is what many vendors ship, and it should work with more or less anything for flashing firmware. Maybe be even using DOSEMU in Linux might work? Generally not, although I never really understood why. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Virtualisation and DRBD
Nigel Allen d...@edrs.com.au writes: We're investigating both virtualisation of servers and High Availability at the same time. Currently looking at Linux-HA and DRBD (amongst others). Keep in mind that both things — HA and virtualization — are actually pretty hard to get working smoothly. Just ask me how it sucks when things don't work right, after another ten hour day fighting a data corruption bug. ;) The idea of DRBD appeals to both me and the client as it means (or seems to at least) that we could add a third (off-site) machine into the equation for real DR. DRBD is two-machine in pretty much any reasonable setup, and the performance for an off-site spare is going to be ... interesting. If you don't have a very low latency, high bandwidth link between the locations then you can expect significant pain and suffering. (The safe DRBD protocol means suffering in performance, the unsafe ones insulate you from pain until you depend on that warm-spare and find out if it actually got all corrupted or not before the failure.) What happens when we then introduce Virtualisation into the equation (currently have 4 x servers running Centos Windoze Server - looking at virtualising them onto one single box running Centos-5). Keep in mind that performance absolutely requires that you have paravirtualized drivers for those kernels. That means picking something where you have good disk and network virtual drivers ... and that probably means not KVM, which sucks. I suppose the (first) question is: If we run 4 virtualised servers (B, C, D, and E) on our working server A (complete with it's own storage), can we also use DRBD to sync the entire box and dice onto server A1 (containing servers B1, C1, D1, and E1) or do we have to sync them all separately? Yes. Specifically: you can do either, or both, depending on how you set it up, and on the capabilities of whatever management software you layer over the basic virtualization tools. Will this idea even float? Can we achieve seamless failover with this. Maybe. You have to be very, very clear on which two of the three attributes, consistency, availability and partition tolerance you need, and make absolutely, without question certain that you deliver on that. To be clear: that means you must absolutely deliver availability (of your HA solution) and non-partitioned connectivity, because you can't live with inconsistency of data between the machines. This is much harder than it sounds: you can easily work out that you have a network cable pulled and have the entire ball of wax fall apart if you are not very, very careful. If not, how would you do it. We just moved from this to delivering iSCSI storage in the back-end, with execute nodes that are going to start shedding local disk. This uses KVM as the virtualization technology, but anything that can talk to raw partitions should be fine on top of this. This gives us two advantages: first, we can scale as broad as we want (and have great performance) by virtue of deploying cheap storage nodes with 6TB of usable disk, tolerance of any two disk failures, and 8.5GB of disk cache between the nodes and the spinning rust. Adding another of those and moving some of the load to another system is relatively inexpensive, and can fairly easily grow with our needs; we can also scale up storage node performance by throwing a more expensive SAS array or server into the mix. (...or just more cache memory, at $100 a GB or so.) The second is that we can deliver reliability without complicating the storage nodes: a virtual machine can use Linux software RAID to mirror, stripe, or otherwise combine multiple iSCSI LUNs inside the virtual machine. This gives us similar performance and redundancy benefits to using local storage to back those devices, including the ability to lose a storage node and have the machine continue to work. This does mean that, unlike a design where replication is directly between storage nodes, we send writes out N times for N targets from the processing node — but that isn't any more bytes over the network overall, and we are not short on network capacity. (Plus, dedicated storage links on a bunch of the busier machines make this work without interference with public services.) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Backups
DaZZa dagi...@gmail.com writes: On Sun, Aug 22, 2010 at 4:54 PM, james j...@tigger.ws wrote: I've spent many hours with pencil and paper, I certain, but am asking in case someone older-n-wiser can offer sage words: [...] Yup, that's the biggest failings with most commercially acceptable backup regimes. It's an offset of cost (in tapes) against reliability. If you want to be 99% guaranteed[1] to be able to recover any file which was saved, your only option is to take a daily full backup. Any grandfather/father/son schema will eventually lead to the possibility for files going missing. *nod* For what it is worth, this is why my usual backup deployment is wonderful in the common case (backup server is alive), and very, very slow in the worst case (backup server isn't). Specifically, I deploy BackupPC or some similar online, disk-based, deduplicating backup system to provide the vast majority of operations. This gives me good responsiveness to most failures: lost file or machine? No problem, since the data is there on disk, and you are not very far from recovering it to whatever target you need. For disasters tape is still good: take regular full dumps of the backup filesystem (or with incrementals, if the cost/benefit works for you) to allow you to recover the backup server if you lose it. That makes a full recovery harder: you have to rebuild the backup server, then build whatever servers are critical. OTOH, it also makes for faster performance in that second phase of recovery because you are no longer limited by tape restore speed after that one machine. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Re: GRUB2 + RAID-1 on debian?
Mr A Tomlinson an...@allsaints.nsw.edu.au writes: I have no experience with Debian, RAID-1 (software) and Grub, but I use it on numerous low end server Fedora installations. [...] This site/article shows how to install grub to the 2nd hdd: http://lists.us.dell.com/pipermail/linux-poweredge/2003-July/008898.html While this one shows the hdd replacement method to rebuild your arrays: http://www.howtoforge.com/replacing_hard_disks_in_a_raid1_array Those are both grub 1 documents; grub 2 is a ground-up reimplementation that substantially changes things. One of the changes, pleasantly, is that it finally understands things like software RAID internally to grub, so that sort of issue is much reduced. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] A distro which recognises Wi-fi on Asus eee 1005p? -- thanks for suggestions
Jon Jermey jonjer...@gmail.com writes: G'day Jon. It would be *really* nice if you could follow the same quoting style as the rest of the thread; it makes it much easier to foll.w *nod* The real problem is not that Linux is hard to install: Windows is just as damn hard, and just as painful, for non-technical users. The problem is that when you buy your machine it comes with Windows installed for you, by someone else, and you don't have to worry about it. To me the issue goes somewhat deeper: from my limited perspective as a hardware novice, I just can't see why different drivers are even necessary. Let me educate you: because the hardware is different, which is because the vendors are lazy, and because ... As far as I can tell one wi-fi card does exactly the same things as any other wi-fi card: ... there are some pretty big variations in what the cards can do, to date, and networking is one of those areas where performance differences are still found, and where the activities of the hardware are complex. is is too much to ask that the hardware should be constructed so that it works with old software which is already out there and functioning perfectly well? Obviously, yes. Otherwise there would be a standard interface for wifi drivers, like we have in USB with the UHCI, OHCI, EHCI, and other standards. :) I accept that when there are technological breakthroughs the drivers need to change; but what we seem to have at the moment is a rerun of the old Apple/Apricot/Microbee/Commodore/Amiga hardware wars with each (wi-fi card, scanner, printer...) manufacturer refusing to run software -- i.e. drivers -- just because it was made for a different piece of hardware. Neither your statement about the old ... hardware wars, or about drivers, is accurate, so there isn't much response possible to this. Surely making a new piece of hardware that will fit into an existing system should be the responsibility of the hardware manufacturer, not the user OR the operating system manufacturer. Why? Seriously: why should the hardware vendor be responsible for paying out the significant amount of money required to support your boutique little OS? If you want to run whatever software you please, why shouldn't you pay directly for the cost of driver development?[1] Isn't it a bit like the printer manufacturers trying to stop you using generic ink by sneaking microchips into their cartridges? In some ways, but not very many of them, and not very similar. A much better analogy would be that a vendor who refuses to distribute hardware programming documentation is like a microchipping ink vendor: In that case both vendors are actively trying to stop you using their system the way you want, rather than just giving you all the information about the hardware and a hearty you want a driver, you know where to find GCC. Daniel Footnotes: [1] ...and you do, even in the FOSS universe: there, you pay by waiting longer to get drivers, rather than by paying more money to get them.[2] [2] ...or waiting longer *and* paying more money, as many commercial OS implementations show is quite possible. :) -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] A distro which recognises Wi-fi on Asus eee 1005p? -- thanks for suggestions
Ken Foskey kfos...@tpg.com.au writes: On Wed, 2010-08-11 at 06:08 +1000, Martin Visser wrote: Jon's experience probably really demonstrates why Linux isn't going to go mainstream anytime soon. While I would say 90% of people are going to have hardware that just works with the most current release of most distros, it is the 10% that have issues that really stings. [...] Installed windows on non-mainstream machines lately. You have to find drivers, have conflicts of dlls and other things. *nod* The real problem is not that Linux is hard to install: Windows is just as damn hard, and just as painful, for non-technical users.[1] The problem is that when you buy your machine it comes with Windows installed for you, by someone else, and you don't have to worry about it. Daniel Footnotes: [1] Heck, it sucks for technical folks too, a lot of the time. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] making ip adress stick rather than DHCP
Voytek Eymont li...@sbt.net.au writes: On Fri, July 30, 2010 2:24 pm, Ben Donohue wrote: [...] I guess I need to disable dhclient, is that what caused the problem ? Well, if it is running it will keep renewing a lease, so yeah. Kill it if you have the static configuration ready and all. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Multiple server roles on one box
dave b db.pub.m...@gmail.com writes: On 29 July 2010 14:40, Daniel Pittman dan...@rimspace.net wrote: dave b db.pub.m...@gmail.com writes: On 28 July 2010 12:23, Matthew Hannigan m...@zip.com.au wrote: On Tue, Jul 27, 2010 at 04:04:05PM +1000, Ben Donohue wrote: [ ] How about a DNS, squid and web server with multiple name based virtual domains on the same box? Is doing the above really dangerous on a fully patched and up to date system? lso depends on the webapp. I'd be more comfortable with java (especially with security manager on) which is after all another form of vm. Java is like php, there are also language flaws coming out to bite you real soon. /me mutters something about OH MY THEY ESCAPED FROM THE JVM. Do you have a reference for that? Here is a recent example :) http://blog.cr0.org/2009/05/write-once-own-everyone.html You can finder older examples as well :) Thanks. That saves me searching around to try and find the same information myself. :) ...but why? What actual security value does that add, compared to the vanilla kernels which do, oh, everything listed in their bullet point feature list, and out of the box covers over eighty percent of them? Good :) - but not chroot break out prevention, further aslr improvements etc. Mmmm. Most of the non-merged features are the ones that are fairly heavily disputed WRT security value, though, are they not? Anyhow, actually telling people why you recommended this was my core point, not to argue about the actual value of the individual items, so if you don't feel super-enthused about responding neither do I. :) Pro tip: asserting that an RBAC system will increase security is silly without actually understanding how it will be used; people can do things just as badly with RBAC as without. Sure, but grsecurity also has some other features :) That was a subset list of the issues, but a fair response to what I wrote. ;) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] making ip adress stick rather than DHCP
Voytek Eymont li...@sbt.net.au writes: I have am old clunker with Centos 5.x, it appears it developed NIC probs, couldn't reach it, when screen plugged in, screen blank on power up, it gave some eth0 messages; I removed the 3COM PCI NIC, starred at it for a while whilst nodding my head, then, put it back in. machine booted OK, BUT, is now on DHCP address, not what it was, fixed IP Strange; I would almost guess that it automatically reconfigured it or something on boot, which is rather strange... I've 'ifconfig eth0 192.168.1.5' ; 'route add -net...' that returned it desired IP OK, but, on reboot, it reverts to DHCP what do I need to make it stick ? Edit the network settings in /etc/sysconfig to set it with a fixed address rather than DHCP. Possibly use the RH GUI tool rather than the command line, if you prefer, to do it for you. :) (tried editing some /etc/sysconfig files, but, it was telling something about hardlinks, so I didn't) I got nothing. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Multiple server roles on one box
dave b db.pub.m...@gmail.com writes: On 28 July 2010 12:23, Matthew Hannigan m...@zip.com.au wrote: On Tue, Jul 27, 2010 at 04:04:05PM +1000, Ben Donohue wrote: [ ] How about a DNS, squid and web server with multiple name based virtual domains on the same box? Is doing the above really dangerous on a fully patched and up to date system? lso depends on the webapp. I'd be more comfortable with java (especially with security manager on) which is after all another form of vm. With php (wordpress, drupal, moodle, or home grown) definitely not confortable. While I also dislike php, what did the last pm's website use ? drupal. What the president of the united states use - drupal. I can keep on going :) Which government website had a big security hole from their CMS? *grin* Not that you are wrong: using tools like WordPress, Drupal, Moodle, and Joomla is reasonably safe, regardless of the language they are written in; their security is primarily dependent on the quality of the authors. One of the PHP problems is that there is so much home grown written in it that, today, it lives in the same place that Perl did years back: as the go-to language for people who don't know enough to write a secure application, so build insecure things.[1] Java is like php, there are also language flaws coming out to bite you real soon. /me mutters something about OH MY THEY ESCAPED FROM THE JVM. Do you have a reference for that? Also, if you really care about the security of the system - install grsecurity[1]. You shouldn't be taking any chances :P ...but why? What actual security value does that add, compared to the vanilla kernels which do, oh, everything listed in their bullet point feature list, and out of the box covers over eighty percent of them? Pro tip: asserting that an RBAC system will increase security is silly without actually understanding how it will be used; people can do things just as badly with RBAC as without. Daniel Footnotes: [1] Yes, IMO, the PHP language design encourages extremely poor practice, and the almost religious avoidance of database abstraction makes SQL injection issues more common, but fundamentally this isn't the cause of the problems — since Perl with DBI wasn't that much better, frankly, on the SQL injection front. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Multiple server roles on one box
Ben Donohue donoh...@icafe.com.au writes: just a question... I'm looking at the possibility of consolidating some servers for a client. If an internal box with DNS and squid were combined, would this be a security risk... as in risky way above normal? No. How about a DNS, squid and web server with multiple name based virtual domains on the same box? No. Is doing the above really dangerous on a fully patched and up to date system? Yes, because you have world-facing services, which is really dangerous. However, it is kind of unavoidable; in this case your biggest risk is going to be the web server, which if it hosts any sort of dynamic content is going to run the risk of compromise. The DNS and Squid servers are basically irrelevant here, and putting them on the same systems is unlikely to increase your practical risk. Any advice please? Do a proper risk assessment, and then work out if putting those on the same system meets your acceptable risk/value trade-off or not, as a business. Regards, Daniel No, seriously, even if it was more risky running them on the same machine, it might be worth $4,000 a month to the business in rack space and power to consolidate them, and so worth doing anyway. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Task bar not working
Jon Jermey jonjer...@gmail.com writes: On 22/07/10 21:17, Chris Allen wrote: I am using Ubuntu 10.4 Since yesterday my task bar (@ bottom of Gnome screen) has been unworkable. It is still there but is always black on black. When I minimise a window, I see it shrink and disappear into the task bar but after that I see no trace of it. It almost impossible to recall it again from the task bar. Is there any explanation / fix for this? http://ubuntuforums.org/showthread.php?t=140473 Ouch! Delete all your settings, just to restore the one application? That would really hurt. You would probably be much better off firing up gconf-editor and looking through the Windows Registry ^W^W gconf database for the menu settings, or hunting for the GNOME panel settings under ~/.gnome and deleting only those. Assuming that is the problem the OP faces, and not rather that some bug somewhere has broken his system without his actually doing anything. Daniel I would consider turning off compositing in your window manager and see if that helps. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Samsung Galaxy S i9000
Simon Rumble si...@rumble.net writes: On 18 July 2010 21:01, Daryl Thompson daryl.francis.thomp...@gmail.comwrote: i am looking at Android powered mobiles and was wondering has any one synchronised the Samsung Galaxy S i9000 with Linux ubuntu as yet and if there was any problems What do you synchronize with a desktop? Anything you want, if you install an appropriate sync provider in Android 2.1 or newer. There is at least one commercial implementation of this, although not focused on Linux at all.[1] So, you could either write some FOSS code to implement a sync provider for the desktop, find one that someone else wrote, or ... Android is really designed to have all your stuff in the cloud. Google Calendars, Gmail etc. Anything else is going to be working against the grain. It might work but it'll be hard work. ... just sync with something in the cloud, like Google, Facebook, MySpace[2], and perhaps soon Twitter. Daniel Footnotes: [1] http://www.markspace.com/products/android/missing-sync-android.html [2] IIRC, they have a contact provider or something, but I didn't really check since I don't use this service myself. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] today's scary thought
Jake Anderson ya...@vapourforge.com writes: On 15/07/10 16:14, Daniel Pittman wrote: [...] We cant be the first people to come across this branch office scenario. Nope. Lots of people have, and wished there was a good solution, but it is a *really* hard problem. The difficulty curve in fixing it looks like a backward L, basically: the most trivial bit is trivial, then the problem more or less instantly gets insanely hard. My goal is to have the branch office get a copy of all the files (think MS office) without hitting performance at either end. something like this rsync thing, with a distributed lock manager would be the solution to 99% of the problem ...only then you pay the cross-WAN latency cost for every file open, at least, plus have to deal with the problem of disconnected operation, so still need conflict resolution, plus... The only problem I can see is if person A in Newcastle wants person B in Sydney to look at their file, they press save and then person B opens it before the lazy copy has moved it over, Perhaps maintain a write lock on the file until its synched? with user definable behaviour in the case of failure. At the moment the branch office is going to be working over a VPN back to the main office, with all the files etc sitting inside VM's, the images of the VM's will get rsynced nightly. Which all in all is a fairly craptacular solution to be honest. Mmmm. For what it is worth, the least-worst solutions that I have found are: 1. Fire up a WebDAV server in each office to store their files, and make sure that it can be accessed through a fully public DNS name.[1] Some document management solutions offer WebDAV as part of their feature set, and might be a good addition to this. IIRC, SharePoint, in an MS environment, is one of 'em. 2. Go buy a copy of http://www.netdrive.net/ for every user that you have. (...or just use a Mac, since they do WebDAV OK too. :) 3. Use it to mount the WebDAV share for your users, because unlike the native Win32 WebDAV support, it doesn't suck.[2] Specifically, it works even if you are using a program that *isn't* Microsoft Office. That gives reasonable performance, akin to HTTP, for reading the remote file, plus some local caching, and it works right no matter where on the Internet your users are because they access a public URL, not a private CIFS share. However, not perfect, especially the server options, and not exactly replicated between sites. I don't know what the latest NetDrive offers in terms of offline operation, either. Daniel Footnotes: [1] Add SSL, authentication, etc to taste, of course. [2] Disclosure: this might not be true in Windows 7, or the latest Vista service packs, but because I have never used them I can't actually say. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] today's scary thought
Jake Anderson ya...@vapourforge.com writes: On 15/07/10 14:10, Matthew Hannigan wrote: On Wed, Jul 14, 2010 at 04:06:17PM +1000, Peter Chubb wrote: You could do this with inotify, with `just a few' scripts around it. Related: http://code.google.com/p/lsyncd/ drives rsyncing with inotify. Actually that looks like a fairly handy tool, I have been trying to work out the best way of keeping files in two offices in sync and drbd seemed like overkill Keep in mind that using rsync like that has absolutely *zero* conflict resolution support, so you are inviting the data-loss fairy to visit when there are concurrent modifications. DRBD, meanwhile, is useless without a cluster file-system on top of it, since you otherwise can't mount the data at both sites at the same time. Sadly, I can't right now advise a better solution than these, however, since it is the main problem I face in trying to bridge two data-centers and provide coherent and sensible file access. The best I can offer, right now, is xtreemfs[1] which will give you fair performance but no local caching, so no disconnected operation. Regards, Daniel Footnotes: [1] http://www.xtreemfs.org/ -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] today's scary thought
Morgan Storey m...@morganstorey.com writes: I bet the manual part of that synchronization doesn't win any points with the users. :) Daniel I know it is a bit un-maintained but what about Unison -- Regards Morgan Storey On Thu, Jul 15, 2010 at 4:14 PM, Daniel Pittman dan...@rimspace.net wrote: Jake Anderson ya...@vapourforge.com writes: On 15/07/10 14:10, Matthew Hannigan wrote: On Wed, Jul 14, 2010 at 04:06:17PM +1000, Peter Chubb wrote: You could do this with inotify, with `just a few' scripts around it. Related: http://code.google.com/p/lsyncd/ drives rsyncing with inotify. Actually that looks like a fairly handy tool, I have been trying to work out the best way of keeping files in two offices in sync and drbd seemed like overkill Keep in mind that using rsync like that has absolutely *zero* conflict resolution support, so you are inviting the data-loss fairy to visit when there are concurrent modifications. DRBD, meanwhile, is useless without a cluster file-system on top of it, since you otherwise can't mount the data at both sites at the same time. Sadly, I can't right now advise a better solution than these, however, since it is the main problem I face in trying to bridge two data-centers and provide coherent and sensible file access. The best I can offer, right now, is xtreemfs[1] which will give you fair performance but no local caching, so no disconnected operation. Regards, Daniel Footnotes: [1] http://www.xtreemfs.org/ -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] today's scary thought
Nick Andrew n...@nick-andrew.net writes: On Thu, Jul 15, 2010 at 04:14:38PM +1000, Daniel Pittman wrote: Sadly, I can't right now advise a better solution than these, however, since it is the main problem I face in trying to bridge two data-centers and provide coherent and sensible file access. Try GlusterFS with mirroring and preference for the local filesystem. It turns out this has a major problem, in the current iteration, for WAN use: GlusterFS currently requires synchronous communication with all replicas for a non-trivial number of operations, so you will pay a cross-WAN latency cost for a whole bunch of (read-only) operations regardless — *and* have to wait for the client to write over the WAN to the remote replica anyway. (Also, AFR you can cause the server to consume unbounded memory and die by writing local data faster than the WAN can flush it, if you don't require it to be synchronous in writing to remote replicas. RedHat are funding development of solid, WAN capable asynchronous replication support, expected to land some time later this year, around the same time that XtreemFS expect to have read/write mirroring of objects implemented. Regards, Daniel As it happens, I have just been investing non-trivial time investigating the options available here. :) -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] today's scary thought
Morgan Storey m...@morganstorey.com writes: What do you mean? it is a manual initial sync to get the files in sync (just copy the different files either way and work out which ones you need to trash or merge) Then startup your unison scripts and let the servers build there indexes then sync. Ah. Yes, that is fair, you can do that. What conflict resolution strategy does it use in that mode? I presume some variant on preserve the lot, which is what I would use. Um, and yeah: you are dead right it can do that effectively. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] today's scary thought
Jamie Wilkinson j...@spacepants.org writes: On 14 July 2010 23:14, Daniel Pittman dan...@rimspace.net wrote: Sadly, I can't right now advise a better solution than these, however, since it is the main problem I face in trying to bridge two data-centers and provide coherent and sensible file access. I think you're going to be out of luck without some fat short pipes to satisfy fast atomic commits to both sides. The cloud way is to have your applications understand there's a replication delay and know how to deal with conflict resolutions, drop the atomicity and integrity constraints to gain some speed. *nod* Factors I am well aware of, but thank you for being explicit about them. I suspect from your mention of file access then you're not dealing with *an* application, but *all of them* and your storage layer API is just POSIX, in which case I wish you well in your pipe procurement endeavours. Our needs vary wildly; in some cases we do want POSIX style file access, with a remote mirror for read-mostly speed-of-access purposes, or where we have a write-mostly application inside the one data center, with fail-over to the other. In others we are quite happy with an eventual-consistency. I mostly focused on files here because suggesting that the OP investigate Reak or Cassandra probably wouldn't fly when they wanted Microsoft Office to access it. ;) Random tangential brainstorm: if your application knew that your POSIX filesystem was being slowly replicated between two DCs, and knew to look in *both* for the same data, and was robust enough to handle the loss of one DC, then it ought to be able to pick up where it left off in the other DC modulo some journalling. Again I suspect this isn't going to help you in the slightest, not knowing anything about your app :) Actually, that is pretty much the model I expect we will use for the most legacy application in our stack, in which we are probably stuck for the next year or so with nothing but POSIX. For the more agile applications my hope is that we can avoid that by, indeed, having the applications aware of the replication issues and all, and using a simple eventual-consistency or last-update-wins vector-clock approach. Daniel Also, lots of different apps, so I might well end up with multiple solutions. A good distributed POSIX FS with replication, eventual consistency, some sensible conflict resolution model, and data center awareness would have been easy enough to use though. If I could have my pony. ;) -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] today's scary thought
Nick Andrew n...@nick-andrew.net writes: On Fri, Jul 16, 2010 at 12:31:42PM +1000, Daniel Pittman wrote: Also, lots of different apps, so I might well end up with multiple solutions. This seems likely. Databases have different consistency requirements to people. One of the attractions of Cassandra is that it allows the client to specify the consistency level required, from none, through to every node ever, or quorum, or whatever. I need to look further at Riak to work out how well their model expresses the same, although as they don't do cross-WAN out of the box it has a lesser problem to contend with. A good distributed POSIX FS with replication, eventual consistency, some sensible conflict resolution model, and data center awareness would have been easy enough to use though. Conflict resolution is the problem. The less of that you want, the more synchronous your filesystem has to become - or expose more non-POSIX filesystem behaviour to applications. *nod* Very true. I think, for most people, the Dropbox model of conflict resolution would be great to have in a file system: Find a conflict, generate two documents, one with each version. Viola, you just punted the hard problem up to a human. Less good for machines, naturally, although a similar process can help. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] today's scary thought
Jeff Waugh j...@perkypants.org writes: quote who=Del Someone asked me today, as they often ask me about things Linux, if I had a Linux replacement for their favourite journal app that they run on their (windows) PC. I asked what that journal app did, and was told: You can set it to track when you open files of various types [in other applications] and how long they are open for.. Further quizzing revealed that you can set it to record when those files were opened, saved, closed, and when and where any saved and backup copies were stored. Wow. What a useful tool for tracking what you do! I mentioned the security impacts of such an application, or even the fact that such an application was possible, and left it at that. Look around for Zeitgeist. :-) ...or snapshot 'ls -l /proc/[0-9]*/fd/' on a regular basis, or better still use one of the task notification hooks that I understand are floating around[1] to capture task creation and exit automatically. Also, what on earth security implications did you see, Del, in being able to see what files you have opened yourself? It isn't like your applications couldn't record this anyhow... Daniel Heck, my Emacs does keep a long history of the files I have opened, since I like to be able to do backward-isearch in an LRU list to get at things I worked on in the last few days... Footnotes: [1] ...in that I have seen occasional discussion of 'em on the kernel list, so presume they have floated out to have a user-space interface by this point, but no nothing beyond that. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] linked folders show different files
Troy Rollo t...@parrycarroll.com.au writes: On Thursday 01 July 2010 19:00:34 Daniel Pittman wrote: On which file system, without causing it serious errors? I can't say categorically that nothing allows it, but it is considered to be a serious violation of the semantics of the system by ... well, most things. You certainly used to be able to do it on the historical UNIX filesystems. Do you mean you could, but it broke things, or you could, and it worked fine, though? I agree you could do it, just like you could unlink a directory. The results were not healthy, though, on any (historic) platform I am aware of. [...] ...while you used to be able to break things as root, on some platforms, it wasn't ever considered a healthy thing to do — at least, to the best of my knowledge on the topic. It was always considered a bad idea, although in some limited circumstances useful. Apparently some backup tools on OSX (or whatever it's called this week) do it. TimeMachine, and apparently it does. Rumor varies about it being possible to do this without being TM under Snow Leopard... Still, a modern system that allows a cyclic graph in the file system. Their VFS cache implementers must love them for putting that into the system. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] linked folders show different files
Ben Donohue donoh...@icafe.com.au writes: I really don't understand what is going on here... I have a folder structure that is replicated several times by linking the base folder A hard-link, or a soft-link? I am guessing the later, since you can't hard-link a directory, but it isn't entirely clear. If you mean cloned by hard-linking all the files then the answer is rather different to what I am about to give you.[1] Some folders down within the master folder I have two files called 1.jpg (a picture of a computer mouse), and 2.jpg (a picture of a computer) When I look at the linked folders via konqueror and with thumbnails on, I see the files correctly. When I delete 1.jpg and then rename 2.jpg to 1.jpg, some folders show a picture of the mouse, others show the picture of the computer. What's going on here? It could be that you are seeing a cache effect, where the system has a copy of the file in either an HTTP cache (if you are accessing this via the web) or a local icon cache. Everything should be a picture of a computer. Why are the linked folders/files not updating with the changes of the file name? Assuming they are soft-linked directories, so the change actually happens to the one single real directory, cache effects. (browsing to the linux box via a windows computer show the correct computer image in all the linked structure) I've turned off caching in konqueror. Maybe it needs more of a kick to do the right thing? The reason I'm asking is that I'm importing the images into a joomla site and the images are now incorrect. I've traced it so far to the linking I think... Given your description, it sounds suspiciously like HTTP caching, but it is hard to be sure. Does the access log for Joomla show that the image in being downloaded by the client, not just a not modified response? Does Joomla maintain an internal cache of, say, rescaled images that might need to be flushed? Daniel Footnotes: [1] Specifically, when you delete a file with hard links, you only remove that one name associated with it. The other links are unaffected. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] linked folders show different files
Ben Donohue donoh...@icafe.com.au writes: I'm embarassed to say that I don't know whether the files/folders are hard or soft linked! How to tell? OK. I am going to start from the very basics here, so please don't be annoyed if I am telling you what you already know — I figure better cover those quickly in case you don't than make you ask again. ;) In Unix there are three parts to a file: one is the raw data itself, which is uninteresting. The second is the inode, which contains things like the permissions, and a list of where the data is found, and all. The inode does *NOT* have a name. The third is a directory entry, which is a record in a directory somewhere that points to the inode, and which has a name. A file actually has zero or more directory entries pointed to the inode, which are used to keep track of it. When there are zero it can still hang around while the file is open, though, because the file handle references the *inode*, not the directory entry. Anyway, a hard-link is when you have more than one name pointing to the same inode. You can see this in the link count field, which is the second field in 'ls -l', or in 'stat filename', or whatever. A soft-link, or symlink, is more like a pointer: it is an inode that contains a path string. When you try to open it the kernel will read that path string, then refer to that object instead. So, the easy way to tell if your image is hard-linked or soft-linked is to look at it with ls: ] ls -l example[12].jpg -rw-rw-r-- 1 daniel daniel 0 Dec 7 2007 example1.jpg -rw-rw-r-- 2 daniel daniel 0 Dec 7 2007 example2.jpg In this case example1 has only one link, but example2 has two. :) If you look at a normal file (eg: added by the software, not manually deleted or changed) you should find out quickly if it has another hard-link or not. :) [...] I'm trying to simplify what I'm doing to try to find out why this is happening. But it seems that Joomla is picking up the cached copy when an image is uploaded rather than the changed file. FWIW, my guess about hard-links would be that you had something that looked like this: /foo/bar/baz.jpg = inode 12 /host/whatever/baz.jpg = inode 12 If you then replace the /foo/bar/baz.jpg *name* with another file, by deleting it and renaming something to the same name then /host/whatever/baz.jpg is not at all changed by this. Which it doesn't really sound like is happening. If I start in a different area with a new file it works correctly. It's only when an existing image is overwritten with the same name that the old image shows up in Joomla but ALSO in Konqueror. Which makes me think it's not Joomla but something in Linux underneath somewhere. Really bizarre! *nod* That is very odd. If you were actually overwriting it you *should* see that content change, at least in the current directory. :/ Does it reflect changed content if you open it in some image display tool /other/ than Konqueror there? How about if you get the md5sum of the image before and after? Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] linked folders show different files
Troy Rollo t...@parrycarroll.com.au writes:
You can hard link a directory (historically done as root using /etc/link or
/sbin/link rather than /usr/bin/ln or /bin/ln).
On which file system, without causing it serious errors? I can't say
categorically that nothing allows it, but it is considered to be a serious
violation of the semantics of the system by ... well, most things.
Certainly all the common file system drivers in Linux, as well as by the core
VFS; see http://lxr.linux.no/linux+v2.6.34/fs/namei.c#L2423 for vfs_link:
2445if (S_ISDIR(inode-i_mode))
2446return -EPERM;
So, you could, but only if you go back far enough that unlink('/') worked,
along with those other nasty ways to break the file system and all. :)
Doing so traditionally requires (1) root; and (2) a direct call to the
link system call (which is what the old /etc/link and /sbin/link did).
...while you used to be able to break things as root, on some platforms, it
wasn't ever considered a healthy thing to do — at least, to the best of my
knowledge on the topic.
However if this is indeed what has been done, then I can speculate as to
what might have happened. I seem to recall that the Linux kernel caches the
file system hierarchy
Nope. That isn't even close to accurate; the way data is cached varies wildly
between different systems, but it isn't especially hierarchical; file data is
usually in the page cache indexed by inode.
in which case there is might be a chance that the kernel cached hierarchy
does not reflect what is on disk.
Well, if the file system was fundamentally broken it would certainly break
caching, but usually in vastly more nasty ways than this.
Hard linking directories is a sufficiently unusual thing to do that it is
possible such a cache was never tested against it.
Actually, it is impossible in anything resembling a recent Linux kernel as
noted, so this categorically *cannot* be the cause of the issue.
Daniel
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Re: [SLUG] LVM
Adrian Chadd adr...@creative.net.au writes: You won't be able to. If you configured them up as a stripe (ie, no mirroring) with interleaving every x megabytes on each disk, you'll basically end up with a virtual hard disk with holes evenly spread out across 1/3rd of the image. I don't know of any (easy) tools to recover from that. LVM, by default, is a boring old linear mapping, so he probably has two disks worth of data ... starting a third (or whatever) of the way through the file system. So, no superblock on whatever. I can think of what I'd write to try and recover -something- but it'd involve writing a whole lot of rather hairy looking filesystem-scraping code. I'm sure there are tools to do this kind of partial data recovery but they're bound to be -very- expensive. The 'testdisk' package available in Debian, and fully OSS, can do quite a lot of data recovery without a file system. It just block-scrapes the device. [...] On Wed, Jun 16, 2010, Gerald C.Catling wrote: Many thanks to all that responded to try to solve this LVM problem. I could not recover any data from the crashed system. I could not find any method of mounting drive 2 or 3 as individual drives and the system would not create a volume group without the now non-existant first drive. Once again, many thanks. I will have to try RAID 1. I strongly suggest that using some sort of RAID is absolutely worth the money. I would also encourage you to try the testdisk tools to recover some of the content of your device: you will probably get back more than nothing back, and that might be worth the hassle. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] LVM
Amos Shapira amos.shap...@gmail.com writes: On 16 June 2010 16:26, Daniel Pittman dan...@rimspace.net wrote: LVM, by default, is a boring old linear mapping, so he probably has two disks worth of data ... starting a third (or whatever) of the way through the file system. So, no superblock on whatever. Why no superblock? The ext3 filesystem (and I guess the most usual suspects) write multiple copies of the superblock across the entire data partition just for such cases. Actually, they do. My mistake. [...] I can think of what I'd write to try and recover -something- but it'd involve writing a whole lot of rather hairy looking filesystem-scraping code. I'm sure there are tools to do this kind of partial data recovery but they're bound to be -very- expensive. The 'testdisk' package available in Debian, and fully OSS, can do quite a lot of data recovery without a file system. It just block-scrapes the device. Right. I used it a couple of times and can tell that without file names it's a chore to wade through all the data and try to find which is important and which isn't. file is handy to do that (as in, e.g., run find ...| xargs file | grep ... and move all files of each type to their own directories). No question there. Thankfully, my only use for it has been recovering photos, and those have nice internal meta-data to help with the process. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] LVM
Gerald C.Catling gcsgcatl...@bigpond.com writes: I am a PCLinuxos user and I have seen references to LVM here ( at SLUG) I have 3 drives LVM'd to give me 1.3TB of storage space on my server. The first drive of this set has died. I am guessing that by LVM'd you mean concatenated together, no redundancy, right? So, basically, you lost one disk and you have lost (more or less) a third of the data under the file system, etc. I further assume that first means the one that contains the superblock, as in the linearly first space on the disk. I was wondering if any of you Guru's could suggest a method of getting any remaing data from the LVM drives, that is drive 2 and 3, that are left. I can identify three approaches: One: Get the dead drive working long enough to actually recover the content from the file system with all the data around. That should work provided died means has a bunch of bad sectors rather than will not respond to SATA commands. Two: Use something that scans the disk and looks for file content, then extracts it. This is unlikely to bring much joy, but might be better than nothing. I have used some of the tools packaged in Debian before, especially 'testdisk', with reasonable success, on *simple* cases like recover JPEG/RAW images from CF cards. For a complex case like a 1.3TB file system, I wouldn't hold much hope for getting a *lot* of content back. Three: talk to the upstream file system developers, and see if they can help identify a mechanism that might recover data without the first chunk. I suspect those are in decreasing order of what you get back, and other than the first that will be very little. Er, and there is another option: pay a data recovery company to do this. It shouldn't cost more than a few thousand dollars for a fairly simple case, and might have a better recovery rate than the alternatives if, say, disk one *isn't* responding, but they can get it back talking for a bit without too much trouble. I have tried rebuilding the set, wg0, but the system want to reformat the drive wg0, just created. Is this formatting going to format the real drives and rather that just the LVM component? All LVM does, in this case, is rewrite the write command so that it talks to the appropriate bit of the underlying physical device. So, yes, because there is no difference between the two. Anyway, for the future: if you concatenate drives, which is all that LVM does, you *increase* the chance of total data loss in your system by the number of devices; in your case — three disks, triple the chances you lose. So, the take-away lesson is that if you intend to do this take one of these three approaches: 1. Format each device as a separate file system, rather than concatenating them, so that loss of one device only takes away one set of data, not all three. Penalty: you now have a PITA job using all that space. 2. Keep good backups, so that when (and it is when, not if) you lose a device you recover much more gracefully. 3. Use some sort of redundancy: software RAID is a pretty decent choice, and is pretty inexpensive these days. Certainly, I bet that the extra few hundred dollars for a second set of disks is less than the cost of trying to recover all that data. Um, and sorry: it sucks that you are now probably going to lose all that data. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] LVM
james j...@tigger.ws writes: On Tuesday 15 June 2010 10:00:03 slug-requ...@slug.org.au wrote: I am a PCLinuxos user and I have seen references to LVM here ( at SLUG) I have 3 drives LVM'd to give me 1.3TB of storage space on my server. The first drive of this set has died. I am guessing that by LVM'd you mean concatenated together, no redundancy, right? So, basically, you lost one disk and you have lost (more or less) a third of the data under the file system, etc. The stuff below is interesting and a reference, but this highlights my favourite rant: Seagate's 'ATA more than an interface' says multiple disks in a machine *will* result in a higher failure rate, maybe much higher. Without needing reference to a vendor study, you can work this out yourself with some very basic probability math, and the MTBF values from the hard disks. Er, and watch out that things like bad batches of disks can result in failures that are *not* independent events in probability terms. So raid is a less worse option than LVM. They serve entirely different purposes, and have some cross-over; you would see the same problem with a RAID0, or RAID-concatenated-space system as with an LVM concatenated space system — or the same redundancy if you used the LVM/DM RAID1 target as if you used the MD version of the same. So, it isn't as simple as saying RAID is better than LVM without talking about the additional details. (...and, FWIW, my preference is *both* RAID and LVM. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Re: LD_PRELOAD
james j...@tigger.ws writes: On Sunday 13 June 2010 10:00:04 slug-requ...@slug.org.au wrote: I can't find any info on this, so it's prodly so obvious that only dumbkorfs ask :-) I have a program using a web cam. All is perfect except that I need to export LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so before running it. How can I compile the links into the code, rather than a PRELOAD env setting? [...] I do have a wrapper, that does work, so thanks What I was trying to learn is how skype did do exactly that. 2.0 had to be wrapped, but 2.1 (beta) uses the cam without preload. Oh. The answer is probably pretty simple: I bet that Skype built their new version with support for the V4L 2 API rather than the long-deprecated version one API. Alternately, they could have implemented the same work-around internally, or even linked in the compatibility code[1], or written dynamic detection for the two API versions, or So, lots of ways. This being a closed application you can't really know. Regards, Daniel Footnotes: [1] ...because that is, y'know, open source. Except they can't actually link that without breaking the license, so the situation is less clear. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Postfix and PCRE filtering
Erik de Castro Lopo mle+s...@mega-nerd.com writes: I'm messing postfix-pcre version 2.6.5-3 from Debian testing. In the /etc/postfix/pcre_table I have the following rule: [...] However, even with all the above, I'm still getting emails with 'casino' in the subject line. Anybody have any idea why PCRE is only working with postfix some of the time? IIRC, header_checks see only raw headers, so anything encoded with RFC 2047 syntax might look nothing like that. For example, 2047 base-64 encoded headers seem popular in spam, and those could contain 'casino' without, y'know, containing 'casino'. Daniel I suggest you use something like amavisd-new which pushes the email through all the relevant normalization before it applies rules like that. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Postfix and PCRE filtering
Jeremy Visser jer...@visser.name writes:
On 06/06/10 20:10, Erik de Castro Lopo wrote:
If I send email from a gmail account with the word 'casino' in the
subject line, the email is rejected and the gmail account gets a
'Delivery Status Notification' message.
However, even with all the above, I'm still getting emails with
'casino' in the subject line.
Anybody have any idea why PCRE is only working with postfix some
of the time?
I have never set up Postfix filtering before, so this is probably a
stupid question, but is it possible the rules you added are only
matching when sent with your e-mail address in the “To:” header (rather
than the “Delivered-To:” header)?
They are not in either: the {header,body}_checks in Postfix are very blunt
tools, inside the MTA.
[...]
Sorry in advance if I’m sending you on a wild goose chase.
It might have helped if you had a better understanding of the tool you were
giving advice about...
Other things you could try is piping the mail through a hex editor to see if
there are any funny U+ characters lurking in there.
...and possibly about the data transfer formats, too, since this is extremely
unlikely: having a NUL byte embedded in the word would, y'know, show up (and
the U+ notation means the Unicode code point with the 16-bit value 0.)
I suspect you actually meant check if the data is encoding in UCS2/UTF16, in
which you would see ASCII characters as a series of regular characters
separated by NUL bytes, because it is a 16-bit[1] encoding of Unicode.
...which you wouldn't try and transit through an email system even if it /was/
8-bit clean, which most of them are not.
Daniel
Footnotes:
[1] ...more or less, leaving aside the complications of the variable width
encoding used.
--
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Re: [SLUG] Oh I hate Shredder
Peter Rundle pe...@aerodonetix.com.au writes: I did the right thing and updated my Linux Mint box with all the latest patches (yes I'm a security conscious goody two shoes). But unfortunately in my haste (orright laziness) I selected all software Thunderbird had been updated to the latest abomination called Shredder which I detest. How can I punt this latest version off my box and go back to one which doesn't think that it's a good idea to cover most of my screen in some non-shrinkable box full of message headers that I don't want to see. Usually, by downloading the older package and installing it by hand. Most distributions make this reasonably practical, more or less. Depending on the architecture you may also have access to older versions through whatever command line package management tool Mint uses; many of them can specify a specific version, and some have access to older versions. That said, I suggest you learn how to resolve the problem: most distributions don't support anything but (close to) the most recent releases of Mozilla products, because upstream are not very helpful if you don't do that, and because they are so incredibly complex and painful that doing it inside the distribution is a losing game. Daniel In other words: even if you can temporarily work around it, at some point you will have to bite the bullet and either move to a less awful mailer, or accept the latest release. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Error in Time() command
Glen Turner g...@gdt.id.au writes: On Mon, 2010-05-24 at 09:02 +1000, Peter Chubb wrote: Actually it doesn't give the whole answer. Wow, thanks heaps Peter. tenzero: so there are 1000 (CONFIG_HZ) samples per second. 250, on my Debian/sid system running 2.6.32-5-openvz-amd64. FWIW. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Virtualization - Whither goes thou?
Nigel Allen prosm...@jamesons.com.au writes: I need to formulate a DRP for a customer and thought that I would ask the slug for it's collective wisdom. [...] First thought was to max out the memory on two of the servers, one for normal running and one as a hot or warm standby, and the virtualize all of the servers onto the two machines. If you can having two machines in an active/active setup is much better: it means that you have to spend less money on idle hardware, and it also means that you don't face a *sudden* load on the passive machine. The reason that last point is valuable is that the time you discover, say, a disk is having trouble is when you start putting load on it, not when it sits idle. Guess when you really don't want to find out you have disk issues on your second machine? An external consultant has already suggested doing this with VMware, installing the ESXi hypervisor on the two main servers and installing a NAS shared between the two systems (hot and cold) so that if the hot server fails, we can simply switch over to the cold server using the images from the NAS. This would let you load-balance also, which is quite nice. Couple of things concern me about this approach. The first is using VMWare rather than a GPL solution. *shrug* You say you plan to run Win32 under this; you are going to need binary PV drivers for the disk and network to get acceptable performance anyway, so you are already looking down the barrel of non-GPL software. The second is where we would install the NAS. Physically, the office space is all under one roof but half the building has concrete floors and half has wooden. (The hot server is in the wooden main office, while the cold server was to go in the concrete floor area. There is also a firewall (a real one) in between the two areas). In your server room, connected by at least one Gigabit link to the servers. Your replicated NAS, of course, lives in your DR location, wherever that is, since you don't want a DR solution that works as long as the server room never catches fire[1]. Questions: 1) Can anyone offer any gotcha's, regardless of how obvious they may seem to you? ESXi hardware support is exciting, make sure you have capable hardware. Pay for commercial support on whatever solution you end up with. At the end of year one, think about dropping it, but keep it until then. Test. If you don't test this stuff routinely it will never, ever work when you need it to. You need PV disk and network drivers to get the performance you expect. You don't need a PV kernel under Linux, though it probably doesn't hurt: almost all the cost comes from the disk and network, and almost everything has PV drivers for those. Make sure you understand what happens if you pull the network from the (or a) active machine without otherwise turning it off — what happens. Make sure you don't spend millions on the best servers, the best NAS, then connect them together through a single network cable that gets cut, bringing the entire thing to a grinding halt. 2) Is there a GPL solution that fit's this scenario? Even if it's not a bare metal hypervisor and needs an O/S. Remember it has to virtuaize both Server 2003 and CentOS KVM can do what you want, but I don't believe there are PV disk drivers available that are open source. You need those. 3) What's the minimum connection we would need between the NSA and and the two servers sharing it? A 9600bps GSM modem, provided your users have very low expectations. ;) More seriously: assuming your disk I/O use is low enough you could get away with 100Mbit, but you really want Gigabit — and, given that you want to live through failure, you want several Gigabit links between the NAS and the servers so that a single *cable* failure doesn't take down your entire system. 4) What kind of speed/bandwidth should we be looking at for the off-site replication. That depends entirely on how much data you write during normal operation, and how big your acceptable window for data loss is. Talk to the vendor of your NAS for details. Generally, though, you want something with very low *latency* more than you want something with very high bandwidth: having a *safe* write means that both the local and DR NAS have acked the write as being on disk. If your latency is 10ms you have at least 10ms delay for every safe write. If your latency is 20ms you double that, and cut your write performance in half... I'll happily take anything else anyone would like to throw at this - suggestions, reading matter etc - it's not an area of great expertise for us having only paddled around the edges with Virtualbox. This is *hard*. Harder than it sounds. Imagine it being as hard as you think, and then it will likely be harder than that. Daniel No, seriously, still harder. Don't forget to test it, and expect to find things go pear shaped and die *anyway* during normal running
Re: [SLUG] new ubuntu 10.4
Jim Donovan j...@aptnsw.org.au writes: I'm still trying to fit 700MB of it onto a 699MB blank CD-ROM. https://help.ubuntu.com/community/Installation/FromUSBStick Assuming you have a 700MB+ USB stick, of course, but those seem to be fairly common these days. HTH, HAND, etc. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] RAID5 Woes
Kevin Fitzgerald k...@tcgtech.com.au writes: I need advice. In a nutshell I have a customer with a 5 Disk Software RAID 5 on an old Fedora Box (The Archive Box). Recently, after a power failure, Two of the drives did not re-join the Array when the machine came back up. DMESG tells me that they are Not Fresh. Take an image of the disks, because if you mess this up you lose the data. The cost of three new disks and copying them won't hurt that much. [...] Assuming the disks are there and OK, How do i Freshen them up and re-build the software RAID array? From mdadm(8) in the 'Assemble' section: -f, --force Assemble the array even if the metadata on some devices appears to be out-of-date. If mdadm cannot find enough working devices to start the array, but can find some devices that are recorded as hav‐ ing failed, then it will mark those devices as working so that the array can be started. An array which requires --force to be started may contain data corruption. Use it carefully. I need to be careful as I dont want to do more damage while trying to re-build. Image the disks first. There is no guarantee of safety in this. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Re: [chat] yet another reason to advocate Linux
David Lloyd lloy0...@adam.com.au writes: Don't let this become a Linux only thing - whether one thinks Free as in FSF, open source as in the OSI or supports proprietary Microsoft...child labour is abhorrent regardless and has nothing to do with the freedom of software. It is, plain and simple, wrong. ...and don't mistake that this actually has much to do with those vendors: the hardware you run Linux on is probably made in similar conditions, as are many of the other facets. (Also, don't mistake that just closing sweat-shops is the best answer, since a terrible job might be better than no job, and sometimes that is the result. Which really sucks, because those conditions *should* not exist, IMO.) Daniel Complexity, ain't it grand. :( -Original Message- From: meryl gnu...@aromagardens.com.au To: slug@slug.org.au Subject: [SLUG] Re: [chat] yet another reason to advocate Linux Date: Thu, 15 Apr 2010 16:40:54 +1000 ... the point of the article was that MS Apple are using exploitative child labour in sweatshop conditions. It's an interesting article, well worth the read. Meryl -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] slow webmail
Jobst Schmalenbach jo...@barrett.com.au writes: [...] this is not a flamebait I know that people like long uptimes, but rebooting **DOES** solve some problems cause you have 888 days, have you considered??? /this is not a flamebait It would probably help this suggestion if you provided some supporting evidence for your position. My first question, as you might imagine, is which problems does this solve? My usual follow-up to that is: are you actually solving the problem, or just the current pain — taking a pain killer rather than fixing the bad back — and probably destroying your chance to find the real cause of the problem in the process? Anyway, without your providing something to back up your statement it is as meaningless as someone asserting the opposite: that rebooting is never the right answer. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
[SLUG] Re: Time Pedantry
Jamie Wilkinson j...@spacepants.org writes: On 1 April 2010 16:56, Daniel Pittman dan...@rimspace.net wrote: Nick Andrew n...@nick-andrew.net writes: On Thu, Apr 01, 2010 at 03:39:00PM +1100, Daniel Pittman wrote: If it was my call, I would probably do the same thing. Way too many developers get simple things like this day has no 2:30AM or this day has two 2:00AMs wrong. That's why Daylight Savings is fundamentally evil. Too much time data is stored in non-canonical formats. ...but the real question is if we love or hate the GMT/UTC difference, and 23:59:61? *cough* :60 *cough* Well, I am glad someone was on the ball enough to notice that. ;) IIRC, :61 is actually a possible but extremely unlikely time value, to account for two leap-second adjustments required in a year, but a quick look around suggests that memory was wrong. So, :60 it is. [...] (And, finally, for anyone who really wants to despair at the whole thing, I give you The Long, Painful History of Time, which is the best write-up I know of about the engineering difficulties of the topic: http://naggum.no/lugm-time.html ) I for one am glad such pages exist. I wish the inventors of time_t had read it. I wish that an awful lot of people had spent an awful lot more time looking at what other systems around them were doing, so that I didn't have this terrible feeling that we are finally dragging our system up to the 1980s for the second or third time. Ah, well. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Re: Time Pedantry
Robert Collins robe...@robertcollins.net writes: On Wed, 2010-04-07 at 12:27 +1000, Daniel Pittman wrote: ...but the real question is if we love or hate the GMT/UTC difference, and 23:59:61? *cough* :60 *cough* Well, I am glad someone was on the ball enough to notice that. ;) IIRC, :61 is actually a possible but extremely unlikely time value, to account for two leap-second adjustments required in a year, but a quick look around suggests that memory was wrong. So, :60 it is. http://www.opengroup.org/onlinepubs/009695399/basedefs/time.h.html The range [0,60] seconds allows for positive or negative leap seconds. The formal definition of UTC does not permit double leap seconds, so all mention of double leap seconds has been removed, and the range shortened from the former [0,61] seconds seen in previous versions of POSIX. Oh, /that/ was where it came from. Thanks. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Best API/abstraction?
Jeff Waugh j...@perkypants.org writes: quote who=Jamie Wilkinson I for one am glad such pages exist. I wish the inventors of time_t had read it. So which language / library has a great abstraction for time and date stuff, helping you deal with the intricacies of this craziness? None of them. Even the good languages have nasty side-bits like a don't be broken switch, and even a perfect language would still have the pain of dealing with political, not technical, issues like timezone-associated dates. Oh, and the fact that date math is *not* simple, since you can't convert between various durations; a question such as how many seconds in a week can only be answered it varies... FWIW, the link I posted earlier was about time handling in Common Lisp, which gets this less wrong than most platforms ... but that document was written because the standard was imperfect. Perl, meanwhile, has good support in various non-core library modules, but many of those have things like a $Class::Date::DST_ADJUST value to determine which behaviour you want for math involving DST and/or leap-seconds. As an example of a well-documented set of complications and how they are handled, the DateTime module does well: http://search.cpan.org/~drolsky/DateTime-0.55/lib/DateTime.pm#How_Datetime_Math_is_Done After you read through the 250 lines of warnings, complications, caveats, and examples of how you can have two completely correct, valid, sensible results that are absolutely in contradiction with each other... Heh. Time. Boy, does it suck. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] OT: windows xp mpeg-2 decoder
Peter Miller pmil...@opensource.org.au writes: Sorry about the off-topic post, but a member of my household has Stockholm Syndrome and chooses to use M$ products. It transpires that XP doesn't include an MPEG-2 decoder as standard. Yes, I know, broken by design. Can anyone tell me a safe and malware-free URL to download a free decoder? http://wiki.multimedia.cx/index.php?title=Ffdshow Not the direct link, because there is ... history in that project, but it should do more or less what you want. As a bonus: all the Windows video stuff should now be much closer to being on par with Linux for ease of use. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Re: SLUG Membership decline
elliott-brennan elliottbren...@gmail.com writes: On Friday 2 April 2010 at 23:59:32, Daniel Pittman wrote a lot. I would just like to say Yeah. What he said. Thanks Daniel. Saved me a lot of work. Do you mind if I put this in my magazine? Happy to help. Anyone can print my why a Linux magazine is hard rant anywhere they like, so long as they send me a copy. The irony of that would be ... so worth it. ;) Daniel Yes, I know it was a joke. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] SLUG Membership decline
James Polley ja...@polley.org writes: On Fri, Apr 2, 2010 at 9:38 AM, Heracles herac...@iprimus.com.au wrote: Also, SLUG should consider producing a magazine for members filled with articles from members including tutorials, reviews of open source software and code snippets, updates on what members are working on and some basics. It could become a benefit of membership. It could be emailed as a pdf to financial members at their slug.org.au email address. Interesting idea. I see one major problem and one major ideological issue though. The problem is the same one we have with talks: you can't have content without someone taking the time to produce the content. We have enough trouble now just trying to round up two people to give a talk every month; I can't imagine getting written content would be any easier. On the other hand, a short article might be easier to produce than a 45-minute talk - and there's no public speaking required, which no doubt would make it easier for some people to participate. For what it is worth[1], my experience is that getting people to produce a *good* written article is much, much harder than getting a good talk out of them. (A good talk is hard to get, incidentally.) When you present you have feedback, and can see if your audience is falling asleep because you are telling them what they already know, or if they are confused because they don't understand a single word you say.[2] In writing you start with tighter constraints on presentation, since written language is much less forgiving and much more formal than spoken language. Add to that the need to use a suitable typesetting system, a vocabulary that benefits from hypertext and demands complex presentation[3], and you are setting a pretty high bar to get a good result. So, yeah, it makes it easier for some people to participate — but I don't think that you get much benefit from that. Writing complex and explanatory documents is hard work for people who do it regularly, let alone those of us who mostly write in less format settings. If we could get the content I like this idea - except for the Emailed as a PDF bit. I think there are much better ways we could present this: for instance, an area of the SLUG website only accessible by financial members; or even a simple private mailing list. Doing the later seems, to me, to be duplicating the strategy of LWN. They do OK with it, apparently, which is a positive. The negative, of course, is that their potential paying audience is about an Internet-million[4] times bigger... If I was pitching this sort of idea I would probably approach Linux Australia with the idea of running it as an Australia-wide publication under their banner. Then you could approach all the different LUGs around the country, and perhaps also NZ, to expand both your contributor-base and your audience. Of course, if I was pitching it I would also go spend a lot of hours talking to people who had published tech magazines over the years. Incidentally, these days none of them are. Every single tech magazine they worked for went bust in the end... Finally, keep in mind that having the magazine is going to demand an editorial staff to produce it. That is a *huge* amount of hard work, even for something that only sees electronic distribution. [...] There are compromises of course; I believe the SAGE-AU mailing list archives used to be members-only for 6 months and then released to the public (although now it seems the archives are completely members-only). We could perhaps investigate something similar. SAGE-AU have been facing something of the same crisis y'all did here, although more serious since they are aiming at higher goals of business-relevance. Their exec are nice people, though, and will almost certainly tell you about their experience with the changes, and why they made the decisions they did. Daniel Incidentally, before someone comes to the clever idea: if y'all do decide to do a magazine, and you do decide to reuse content from the mailing list, make sure you get appropriate licensing. Which, in turn, means you get a real copyright lawyer to OK your strategy. Nothing sucks worse than republishing, as an example[5], my content, then finding out that I deliver a demand for significant licensing fees from you, backed up with my own lawyer and legal threats.[6] Footnotes: [1] ...especially as I am nothing but a freeloader on the mailing list, and only there because I find the variety of discussions in multiple LUGs more likely to produce something interesting. [2] Ever *bad* presenters have a vague awareness of this, although they might not recover well or change approach to reflect it. [3] Doing *good* layout of either GUI or command-line examples is hard. Good layout for things like configuration ... ouch. [4] In other words: much bigger, but I don't know how much. [5] ...using me as the subject
[SLUG] Re: Time Pedantry
Peter Hardy pe...@hardy.dropbear.id.au writes: On Thu, 2010-04-01 at 16:56 +1100, Daniel Pittman wrote: ...but the real question is if we love or hate the GMT/UTC difference, and 23:59:61? Also, do we hate the earthquake that changed the length of the day for messing with our time-keeping? http://www.sciencedaily.com/releases/2010/03/100302084522.htm [...] None of this would be a problem if we'd just switch to decimal time in a single timezone and call it a day. Actually, we would still have to deal with the changing length of the day, and with the increasing difference between our stellar and earth-based times. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Re: Time Pedantry
Rick Welykochy r...@praxis.com.au writes: Nick Andrew wrote: Indeed. The Earth's rotational period does vary slightly (effect of earthquakes notwithstanding). One reason time is hard to deal with sensibly is our insistence on synchronising it to the mean solar day. // off topic Easter Time time ramblings Isaac Asimov figured it out years ago. From memory ... Create a new calendar with 52 weeks of 7 days = 364 days. Add one extra day, called World Day, at the end - 365 days. World Day does not have a day of the week. In this way, every date falls on the same day of the week in every year. Note that this doesn't address the GMT/UT[C01] issue, which is all about the relationship between local time and time-as-seen-by-astronomers, or perhaps more clearly, time as it relates to the actions of things other than our own planet rotating. For leaps years, add an extra Leap day after World Day. It too has no day of the week. To make things precise, every 100 years, there is no Leap Day, but every 400 years there is. That pretty well matches up the solar year to the earth's rotation. I don't find this convincing, FWIW, since it doesn't address issues like every five days in a terribly meaningful day. All it does is translate those into one of two problems: Either you have every five days, except once a year when it is six or seven days between instances, or every five days, but which day changes every year. Unfortunately, we can't just stop the world for world day, which means that we still have unpredictable day/date matching. [...] I don't recall Asimov dealing with the tetchy problem of daylight time. IIRC he thought it was a silly idea, as were the politically motivated time zones. Both views are ... arguably true. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Which bank doesn't use Linux servers?
Jake Anderson ya...@vapourforge.com writes: Jim Donovan wrote: I noticed the following on the Commonwealth netbank site this morning: NetBank, Mobile Banking and Telephone Banking will be unavailable between 2am and 5am EST on Sunday 4 April 2010 to allow for the changeover from Australian Eastern Daylight Savings time to Australian Eastern Standard time. Please take this timeframe into consideration when completing your banking. For updates during this change, please visit: www.commbank.com.au/update. Please press NEXT to access NetBank. Assuming it wasn't an April Fool joke, perhaps it means their databases use local time and the logic won't permit transactions to be entered out of order such as might appear to be if one happened just before the changeover time and another less than an hour later. How quaint! I remember hearing once that Commonwealth Bank servers were always rebooted on Sundays so they'd be less likely to go down during the week. Odds are its more to do with their internal applications which are probably written on cobalt running on CP/M machines or something equally modern. Your probably lucky they even know time zones exist ;-. My money would be on the very boring option, paranoia: If you shut down as many of these systems as possible during the change over, then those systems *can't* go wrong — because they are doing nothing. If you leave them running then, hey, maybe something breaks. So, if you want to look at the cost/benefit analysis the cost of a few hours outage overnight is pretty low, especially if you can schedule it well in advance, and even more so if you can do some other maintenance work at the same time. Meanwhile, no risk of things going wrong during the change-over, which is always a huge PR fiasco even if nothing really bad happens. Daniel If it was my call, I would probably do the same thing. Way too many developers get simple things like this day has no 2:30AM or this day has two 2:00AMs wrong. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Time Pedantry (was Re: [SLUG] Which bank doesn't use Linux servers?)
Nick Andrew n...@nick-andrew.net writes: On Thu, Apr 01, 2010 at 03:39:00PM +1100, Daniel Pittman wrote: If it was my call, I would probably do the same thing. Way too many developers get simple things like this day has no 2:30AM or this day has two 2:00AMs wrong. That's why Daylight Savings is fundamentally evil. Too much time data is stored in non-canonical formats. ...but the real question is if we love or hate the GMT/UTC difference, and 23:59:61? Daniel Also, do we hate the earthquake that changed the length of the day for messing with our time-keeping? http://www.sciencedaily.com/releases/2010/03/100302084522.htm (And, finally, for anyone who really wants to despair at the whole thing, I give you The Long, Painful History of Time, which is the best write-up I know of about the engineering difficulties of the topic: http://naggum.no/lugm-time.html ) -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] ubuntu network manager dns
Ashley Maher ashley.ma...@didymodesigns.com.au writes: I am used to putting in the IP of a dns server into resolv.conf and all good. It was very frustrating to find that most of the listed tesltra dns servers failed. host allowed me to check what servers are working quickly. FWIW, I got very sick of this years and years ago, so I took to installing the distribution packaged version of bind on my machine and configuring the system to use localhost for name resolution. That gives a pretty solid resolver that just works(tm) anywhere, and while there is a tiny increase in first-access latency to sites I can't say it has any significant practical drawbacks. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] ubuntu network manager dns
Nick Andrew n...@nick-andrew.net writes: On Sun, Mar 28, 2010 at 11:23:35AM +1100, Daniel Pittman wrote: FWIW, I got very sick of this years and years ago, so I took to installing the distribution packaged version of bind on my machine and configuring the system to use localhost for name resolution. dnscache works well for that too. See http://cr.yp.to/ or http://tinydns.org/ or http://github.com/nickandrew/djbdns Oh, cool. Someone talked DJB into relicensing dnscache so that it can be distributed patched, rather than requiring the original. That must make life better for folks like you who want to use it. Anyway, I have a bit of an aversion to the software: aside from the (formerly) awful license conditions, I had a couple of clients who ended up with really nasty problems from dnscache. (Executive summary: probably not a problem any more. ;) Way back when a 256/64 kbit ADSL connection was fast and expensive, a couple of places I supported used software that incorporated dnscache, and had the ability to use DNS RBLs for inbound email. So, it turns out that dnscache had a fixed ten second timeout for a response from the upstream DNS server. If it receives a reply outside that window it will reject the reply; it also resends queries if they time out. Apparently, though, if you manage to list enough RBLs you can get in a situation where dnscache is sending requests, which all time out because the link RTT is more than ten seconds — just from the load of sending retransmitted queries. Which meant that two or three emails inbound at once could result in a situation where their network link got saturated, and stayed that way until dnscache gave up on all the queries. Gosh, was that fun. Anyway, these days that is unlikely to be a problem: either the code will be patched to play nice, or the increase in bandwidth makes the odds of breaking pretty slim. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] ubuntu network manager dns
Martin Visser martinvisse...@gmail.com writes: Also be aware that there some ISPs tend to a few things with DNS 1. Some do block access to their DNS from outside of their network. You mean *recursive* DNS, not authoritative DNS, right? [...] 2. DNS can be used to help direct the subsequent application traffic to particular managed servers. For instance, Internode provide unmetered content to their customers, one of which is the ABC iView service. However at least in some part, probably because of the use of content-delivery networks, Internode ask to make you use their DNS. Really? That bites. Most CDN networks have arrangements so that this works regardless of which DNS server you use. Can you point to an official document stating that? I checked, and I found some unofficial comments on Whirlpool, but nothing I consider authoritative from Internode. :( Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] A little script help
Amos Shapira amos.shap...@gmail.com writes: On 16 March 2010 18:18, Josh Smith joshua.smi...@optusnet.com.au wrote: [...] I plan to use this for work for the (DRN) I have run out of things to put as my password and I am not aloud to have the same password twice I use pwgen to generate my passwords and a password vault to keep them as a backup. I advise 'apg', which is packaged for most distributions. While it has some theoretical weaknesses[1], it is sufficiently strong that it should beat any non-targeted attack. The advantage of it, though, is that it generates passwords that follow the same basic rules of structure that English words do, so they are remarkably easy to memorise and use in practice.[2] [...] 2. Split the loop to three - one which picks a first letter from the uppercase-only string, one which picks 5 characters from LORD and one which picks 2 characters from the digits-only string. Ideally, you would want to rewrite this as a function which takes a candidate set of characters, picks a random character from it, then returns that. Then you could make it easy to template your passwords to whatever length and complexity you need. Regards, Daniel Footnotes: [1] It uses a generation model that doesn't produce perfectly random results, by selecting from the pool of valid results. This introduces imbalances in the generated parts-of-speech in the passwords, allowing you to substantially reduce the search space over a fully random password generator. If you are concerned, and care more about probably-theoretical security then there is a Perl implementation of the same idea which uses a fully-random password generator, and then tests the generated password for compliance to the parts-of-speech model. That removes the bias, and is as theoretically secure as a fully random password when the same number of bits of entropy are included. Obviously, the use of filtering means less bits-per-character. :) [2] Every time I tell someone this, they don't believe me, because it doesn't look easy to memorise. In practice, they never fail to be amazed how well they did committing it to memory after the fact. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] System admin graphing tools
Aleksey Tsalolikhin atsaloli.t...@gmail.com writes: Ken Foskey wrote: We all know we should do it. Provide a monitoring system to see how our system loads are going. I know you got lots of replies, Ken. What did you end up using? You might want to also check out Splunk - it's pretty nifty and quite powerful and will show you how your system loads are going and a whole lot of other stuff too. Personally, I use Nagios for monitoring/alerting and Zenoss to get the pretty graphs of system loads, etc. Best, -at -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] HD Crash - recover?
j blrown gonz...@fastmail.fm writes: Just had my 5 mth old 1 terrabyte Samsung HDD start clicking like crazy when I turned on PC. First and last Samsung HDD - I'll stick to Seagate from now on - never had a problem with them ...just for reference, every hard disk vendor out there has had a bad batch at some time or another — and even without that, there will always be some hardware that dies in the first six months of use. Personally, one failure wouldn't turn me away from a vendor forever, because it simply isn't enough information for any reasonable conclusion. Is there a utility that might recover some of my data? Disk only partially used, divided into 2 x 500mb partitions of ext 4 (I think). Can you actually read the device at all, or is it failing to respond with data at all? If the later, you might try putting it in a water-proof container, in the freezer for a few hours, and then giving it another shot. That may unstick it long enough to get the data off, or maybe just some of it, without substantial risk. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Sticky bit on /var/tmp
Craig Dibble cr...@rootdev.com writes: Does anyone have any thoughts on removing the sticky bit on the /var/tmp directory and setting it to 777? Why would you want to allow unprivileged user to delete temporary files created by other unprivileged users? Something about it doesn't sit quite right with me but I can't so far find any negative impact of doing so. Other than the marginally increased, and probably mostly theoretical in these days of one-user-per-machine, security risk there isn't much. The reason for this is that we have a large amount of data moving through that folder, in the order of more than 100GB. We have cleanup scripts which need to be able to remove files and folders to reclaim space every time a job finishes but the files are created by the user who launched the job, and the control process, and hence the cleanup, runs as a different user. And there we have a problem as the sticky bit prevents the cleanup from running and we have boxes falling over because their disks fill up. I'm fairly sure the first response to this will be Use sudo, as that was our first response too, or store the data somewhere else. Both of these are possible but difficult, the latter exceedingly so. We've tried to think of every sensible alternative but the simplest fix would be to just change the permissions and hope there isn't something which is going to bite us as a result. ...er, is there any strong reason to run the cleanup script as some user other than root? Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] Sticky bit on /var/tmp
Craig Dibble cr...@rootdev.com writes: Quoting Peter Miller pmil...@opensource.org.au: On Wed, 2010-03-10 at 10:07 +1100, Craig Dibble wrote: Does anyone have any thoughts on removing the sticky bit on the /var/tmp directory and setting it to 777? [...] If you're curious, this is a large render farm controlled by a homegrown job scheduler, the users submit jobs and the scheduler takes over - hence our current problem. See, this is why I like tools like Condor, PBS, or the Sun Grid Engine. You get to let other people pay the big money to build features like cleaning up for you, so you don't have to. You get to play more golf.[1] Might it be easier to provide a compatible API to users, and replace the inside with one of these tools? We have pre and post hooks available though, so maybe doing a chmod or chown on the directory at the start and end of every job would suffice to keep everyone happy? If you can do that, can't you just remove the files as root? Unless you are running on some strange platform that allows giving away file ownership to unprivileged users or something... Daniel Footnotes: [1] ...for some value of golf attractive to you, of course. ;) -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] FAX server or gateway or some other solution
david da...@kenpro.com.au writes: Ben Donohue wrote: I have a requirement to have a FAX at home. I have vmware ESXi with CentOS virtual machines and would like to create a FAX machine hooked into a modem to the phone line. However solutions like Hylafax require a serial port but VMware does not support serial ports. (yet) quote September 3, 2007. innotek today released VirtualBox 1.5.0 for Windows and Linux. snip Version 1.5.0 also adds support for serial ports /quote That suggests that Virtualbox will do serial ports although it doesn't prove that it actually does - I haven't tried. I do know from experience that you can switch an existing vmware virtual machine over to virtualbox and that it makes life a lot easier after you do. I almost suggested something that made a similar assumption to you: that there was a host Linux or Windows OS that could, for example, run additional software. I noted the ESXi designation, which is the minimal bare-metal hypervisor, and doesn't run on top of another platform — so, moving would be a major, not minor, shift. [...] I'm just looking for some solution to mostly SEND faxes... less of a must having to RECEIVE faxes. But I suppose it should work both ways (in and out) if possible. [...] I'm still searching but open to idea's. Perhaps someone has found a perfect FAX solution already? Last time I needed personal fax I used these folks: http://www.utbox.net/ Honestly, dealing with faxing, and Hylafax, for work makes paying someone else to care still sounds like a *really* good deal to me. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] mount LVM from Ubuntu live CD
Michael Chesterton che...@chesterton.id.au writes: On 19/02/2010, at 1:41 PM, Daniel Pittman wrote: Try booting the kernel with 'init=/bin/bash' on the command line, and then: ] mount / -o remount,rw ] passwd root # ...and give it a good password ] mount / -o remount,or ] sync; sync; sync # wait thirty seconds, because paranoia never hurts ] sync; sync; sync; reboot That should get you past the problem, at least as far as the next issue. i guess that's mount / -o remount,ro Yup. I'm curious about the order of the read-only command, and the syncs. I did assume there would be nothing to sync on a read-only file system, but I take it sync works below the file system level? sync instructs the kernel to flush out dirty blocks now; indeed, a read-only file system generates no dirty blocks, but while you had it mounted read-write you would have generated them. Mounting to read-only doesn't necessarily flush all the dirty data, so you need to manually trigger that. In theory, one sync should do it; in practice, this has varied over the years, so the ultra-paranoid version certainly doesn't hurt. :) Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] mount LVM from Ubuntu live CD
Jeremy Visser jer...@visser.name writes: On 19/02/10 13:41, Daniel Pittman wrote: ] mount / -o remount,rw ] passwd root # ...and give it a good password ] mount / -o remount,ro ] sync; sync; sync # wait thirty seconds, because paranoia never hurts ] sync; sync; sync; reboot Just be aware that you don't get a lot of nice things like, oh, some of the flush on shutdown behaviour that you do in a normal boot. Shutting down from the GUI, or typing 'halt' isn't magic. It doesn't magically do anything that sync doesn't. How else do you think that the logic works when you shut down? ...perhaps my working wasn't clear, as you seem to be restating my point? Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] mount LVM from Ubuntu live CD
Martin Visser martinvisse...@gmail.com writes: I don't get how sync will write anything to a ro filesystem. That seems to be to break a fundamental kernel and filesystem principle. ...ah. Um, it doesn't write anything to the file system, as such. It triggers the dirty pages in the kernel cache to write out to their block devices. The read only switch in the file system, and to some degree the file system itself, are at a higher level, so are not involved especially. (...and once the file system is read only it *should* not generate any more dirty blocks, although occasionally bugs could trigger this.) I would have thought either the remount would either force a flush of dirty blocks before it switches to ro, or alternatively those blocks still dirty at the time of the remount end up in the bit bucket. Nope. Not least because you *can't* make that assurance: the blocks written may be in flight on the HBA, or even the network, between the file system and the magnetic storage. Also I have seen this 3 sync incantation before. It dates back a *long* time, well before Linux. These days it is seldom, if ever, necessary, but old habits die hard. It seems to me that all you are doing playing snap with processes that might have stuff to write but hasn't been flushed. If there are active processes writing, sure. It used to be, once upon a time, that sync didn't (guarantee) to write every dirty block on the system. (Theoretically, with enough block layers between the magnetic storage and the page cache you could perhaps still race to the same conclusion or so, but probably not.) After any sync and before the final shutdown I presume any running process is at liberty to create new dirty blocks that may or may not make it to disk in time. Correct. If you mount the file system read-only, though, you can be confident that no *new* dirty blocks are being generated by that file system, absent bugs. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
Re: [SLUG] RAID and LVM
Tony Sceats tony.sce...@gmail.com writes: Slower, though ... is a bit of a strange claim. Not because it is false, but because the answer is complex: you can, for example, double read speed and halve write speed, using a two disk RAID 1 array ... in the ideal case. I must say I'm curious about this, because I have always assumed that for a RAID 1 the write speed would be roughly the same as a single disk, not halved.. Sorry, you are quite right. It should write at approximately the speed of a single disk, and read at twice the speed. More or less. I shouldn't post while I have a cold, because it makes my thinking bits not working. [...] If this is true, I guess the reason would be that the same data travels over the same bus twice before the operation can be said to be completed, therefore halving your write speed. This is the only point it actually cuts speed below a single disk, and that takes more than two disks even on some of the less good modern systems. Sorry. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
