Re: [CentOS] recommendations for copying large filesystems
Mag Gam wrote: I need to copy over 100TB of data from one server to another via network. What is the best option to do this? I am planning to use rsync but is there a better tool or better way of doing this? For example, I plan on doing rsync -azv /largefs /targetfs /targetfs is a NFS mounted filesystem. Any thoughts You are going to pay a large performance penalty for the simplicity of using a local form rsync. Between the substantial overheads of rsync itself and NFS you are not going to come anywhere near your maximum possible speed and you will probably need a lot of memory if you have a lot of files (rsync uses a lot of memory to track all the files). When I'm serious about moving large amounts of data at the highest speed I use tar tunneled through ssh. The rough invokation to pull from a remote machine looks like this: ssh -2 -c arcfour -T -x sourcemachine.com 'tar --directory=/data -Scpf - .' | tar --directory=/local-data-dir -Spxf - That should pull the contents of the sourcemachine's /data directory to an already existing local /local-data-dir. On reasonably fast machines (better than 3 Ghz CPUs) it tends to approach the limit of either your hard drives' speed or your network capacity. If you don't like the ssh tunnel, you can strip it down to just the two tars (one to throw and one to catch) and copy it over NFS. It will still be faster than what you are proposing. Or you can use cpio. Rsync is best at synchonizing two already nearly identical trees. Not so good as a bulk copier. -- Benjamin Franz -- Benjamin Franz TIA ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] SELinux - way of the future or good idea but !!!
On 11/28/2010 09:31 AM, Benjamin Franz wrote: [...] And then, one day, it won't work. Worse - it doesn't always *log* what it is doing in a way that you can figure out. Occasionally not at all. So you spend a few hours poking at the system until you try the magic of turning off SELinux. And then it starts working again. My experience is that *unless you have a system configured exactly like the defaults*, SELinux is prone to suddenly deciding after an update that it doesn't like your configuration anymore. Once because an update to SELinux changed the labeling on an existing directory tree - blowing away my own applied labeling with no warning. And there are even RH supplied rpms that *do not work* with SELinux without being SELinux being tweaked first. And in an exact example of this, today I needed to update some WordPress (WP) installations. Only, for some reason the FTP based autoupdater didn't work today. You guessed it - SELinux had struck again. I have left SELinux active on this machine because I don't trust WP not to get hacked. I went out of my way to make the system as SELinux friendly as I could when I built it because of this. It has had SELinux active right from the start. But something in the normal yum system updates or other routine system operation over the last several months apparently caused the system to mis-label part of the directory tree making it so that FTP (which is only allowed from the localhost to support WP updating) could no longer access some directory trees. No idea why: I'm the only person who has logged into the machine since March - and I only log in to run updates. It worked on April 26th - but not today. My fix today? I temporarily disabled SELinux, ran the WP updates, touched /.autorelabel and rebooted the machine. And mysteriously the FTP problem is gone now. This isn't the first time this has happened on this machine. If I wasn't so specifically paranoid about WP, SELinux would be disabled on this machine as well. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] SELinux - way of the future or good idea but !!!
On 12/06/2010 06:06 AM, Daniel J Walsh wrote: Did you take a look at the AVC messages? Are you running setroubleshoot? Yes to both. Usually running something like restorecon -R -v /var/ftp would have cleaned this up, if it is a simple mislabel in /var directory. The point is *I shouldn't have to*. A stable system should not have breakages from SELinux where 'for some reason' a directory tree got mislabeled during updates. And yet it does. I enable SELinux on only a handful of my systems - and most of those systems acquire SELinux related problems at least once ever year or two just from normal updates. While SELinux continues to do stuff like this, it will remain disabled on the vast majority of my (and many other people's) systems. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
[CentOS] Nerd rage (Was: IPV4 is nearly depleted, are you ready for IPV6?)
On 12/08/2010 07:03 AM, Scott Robbins wrote: Honestly, I had no one in mind. I remember in an effort to get a life outside tech, I joined a mailing list for something else. I hadn't realized how most people top post, don't trim, and still use aol. It really is worth noting that the bottom-post convention used on many technical lists *is not* how most of the planet now does email or other electronic communications. The rage we see here over it is really just another technical 'religious war' by people who don't tolerate change well. In reality, it doesn't matter much for most things either way and far more harm is done by the howling over it than using either convention actually causes. I still remember the rage sparked on the Usenet by some old timers when people started using JPEG and MIME rather than GIF and uuencoding. Oh, the horror of it. Oh, BTW: vim over emacs. ;-) -- Benjamin Franz Asperger's are wonderful people but they can be very difficult to get along with. The expression would argue with a signpost comes to mind. - John Wilkins, blog comment, May 24 2006 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] What NAS device(s) do you use? And why?
On 12/11/2010 09:24 AM, Rainer Duffner wrote: With 100TB, DIY is out of the question ;-) I wouldn't say that. It would be...challenging...but not out of the question. But Aberdeen (note - I have no financial interest. They are simply someone I've seen marketing Linux based SAN/NAS machines before) has some not too insane pricing for a ready-built 132TB machine. http://www.aberdeeninc.com/abcatg/8UDS-Nehalem-Linux-NAS.htm -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] adobe flash
On 12/13/2010 12:05 PM, Sven Aluoor wrote: 2010/12/13 Pintér Tibortib...@tibyke.hu: On 12/13/2010 06:30 PM, Ritika Garg wrote: I have CentOS5.5 installed in the system. After updating the version of firefox, the videos are playing on the internet. Earlier the message flash player download required used to come. so what? is that a problem? you want your message back? maybe because of the many security vulnerabilities? Because Flash is proprietary, non-free? Because flash reduces battery life? Because flash is prone to crash? Flash is mainly used in ads? There are so many reasons why Flash is crap :-) So disable it if you don't want it. Tools - Add-ons - Plugins - Shockwave Flash - 'Disable'. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] OT: programming language for morons (newbie friendly language in Open Source world)
On 12/13/2010 04:16 PM, Les Mikesell wrote: On 12/13/2010 6:08 PM, Benjamin Franz wrote: I don't know about that. I started on Apple Integer BASIC back in 1980, dropped to assembly on multiple platforms, and eventually ended up doing OO style design in Perl in the 90s *before* it officially had OO. I remember my sister commenting something to the effect that I seemed to design code mentally in OO styles regardless of the actual implementation language a decade or so ago. It's one thing to build complex data structures (like making your basic C data type array of struct ...) so you can iterate nicely, but something else to think the code belongs to it. Thinking the code belongs to the data just a mental model. One of many that may be used or not used at need for the exact same code. But never make the mistake of thinking any of them are The Truth. A good programmer switches mental models as needed and is not wedded to any of them as The Truth - merely as *convenient to the task*. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Tar so slow! Is there anything faster?
On 01/06/2011 05:47 AM, Dotan Cohen wrote: I need to tar up a good 100 GiB of files, but tar is progressing at a rate of about 1 MiB per second. Is there something, anything, faster? tar is normally screaming fast unless you use bzip2 compression (or gzip compression on an underpowered CPU). Provide details: What are you tarring, how are you invoking tar, what hardware are you running on (hard drive types, cpu type, etc). -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Server reboots unexpectebly.
On 1/16/2011 9:24 AM, compdoc wrote: I've seen one memtest iteration pass, but 2 or 3 were needed before a failure showed up. That's not usually the case, though... I have a server right now which passed three memtest iterations but throws intermittent errors on one DIMM when it gets warm enough (warm enough being about 2 or 3 C warmer than the normal system temp under full stress test load with all covers on in my build environment). It isn't really common - but it does happen. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] How to disable screen locking system-wide?
On 01/20/2011 02:55 AM, Rudi Ahlers wrote: I don't agree with that, sorry. A few years ago one of our staff members decided his salary isn't good enough so he started a side-line business, on our company time. He stole some of our client's data (contact details, emails, and even contracts) and sold it to 3rd parties. This went on for about 6 months before we actually realized what was going on. Needless to say, he was fined heavily and sent to jail for 3 years. So, I don't care if you feel the PC is your's, as long as it's a company PC, with company data and company property, we will take a look at the data on it. I'm not talking about your home / private PC, that's an altogether different story. You are talking completely different issues. Allowing anyone walking past a machine to sit down and do whatever they want (which is stupid) is not in the least the same as having administrative access and auditing by IT (which is smart). If you don't have full administrative access to the machine *independent* of people's day-to-day login accounts you are doing it wrong and need to hire a competent IT admin - because your current one doesn't know what heck they are doing. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] mysqld status discrepancy
On 01/25/2011 09:19 AM, ken wrote: Bug, explainable, or expected?? Checking the status of mysqld as root, then as a regular user: # /etc/init.d/mysqld status mysqld (pid 4806) is running... $ /etc/init.d/mysqld status mysqld dead but subsys locked As expected. The PID file for MySQL is not normally world readable and therefore the script cannot determine the PID to check if it is alive if run as an regular user (other than as the 'mysql' user or 'root'). -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Recommendation for a Linux alternative to Centos - ATH9K disaster
On 01/25/2011 09:49 AM, Always Learning wrote: I persuaded a reluctant friend to buy a new computer. I enthusiastically extolled the joys and benefits of Centos and promised to install it on his new machine - dual booting with Micro$oft Windoze 7. [...] For a new laptop your best hope for a successful native install is probably Ubuntu 10.10. Laptops in particular are difficult platforms for hardware support and CentOS5 is not 'cutting edge'. If you want CentOS on it to work well, you will probably need to wait for CentOS6 - which could be a month or two. An alternative I've used is to install VMware Workstation on top of Windows and install Linux into a VM. Running fullscreen the practical difference is nil. Then you by and large get the laptop hardware support gratis from the windows layer including things like wireless and video drivers drivers. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Ext4 on CentOS 5.5 x64
On 01/27/2011 07:37 AM, James Hogarth wrote: On 27 January 2011 15:06, Sorin Srbusorin.s...@orgfarm.uu.se wrote: Hi all, For those of you that have been using the ext4 technology preview on CentOS 5.5, how has it panned out? Does it perform as expected? How do you feel the stability, creation of the FS and the administration of it is? Ideas and comments welcome. Well for what it's worth it worked out well enough for Redhat that it is a fully supported filesystem in 5.6 and the default in 6.0... same admin tools as ext3 so not much to learn as it were... However, be very, ah, *cautious* about trying any ext4 options beyond the RH defaults. I tried creating some with extents and other non-default options yesterday and it immediately triggered kernel panics when I tried to mount the resulting file systems. On the other side, I've been running default ext4 options on CentOS5 on some machines for years now with no hiccups at all. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Any update on 5.6 / 6?
On 02/15/2011 07:59 AM, R - elists wrote: Eero, that is great, as long as you consider and actually donate to CentOS regularly statistically, most people that download or use CentOS, do not donate. That, statistically speaking, could be influenced by the fact the monetary donation page has been 'down' for around one and a half years (ever since the centos 'ownership fight'). I can personally vouch for the fact my company was looking to donate money - only to be stonewalled by the lack of a way to do actually do so. Money has these great virtues: It can be accumulated in small increments from people who can't afford large increments. It can be exchanged for physical objects like servers. And it can be used to pay (even if only on a part time basis) people to do specific jobs. I highly recommend it. ;) -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 03/27/2011 02:57 AM, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). I'm currently using Ubuntu Server 10.04-LTS as a host for KVM running CentOS5.5 guests I migrated from VMware Server 2. Works fine. A nice feature of current generation KVM is that you are supposed to be able to do live migration even without shared storage (although I haven't tested that yet). I wrote some custom scripts to allow me to take LVM snapshots for whole-image backups and I'm pretty happy with the who setup. The only corners I encountered were 1) A lack of documentation on how to configure bridging over bonded interfaces for the host server. It turned out to be fairly easy - just not clearly documented anyplace I could find. 2) The default configuration for rebooting/shutting dow the host server just 'shoots the guests in the head' rather than having them shutdown cleanly. :( You will want to write something to make sure they get shutdown properly instead. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos 6 Update?
On 04/07/2011 03:52 PM, Scott Silva wrote: The GPL says they must release source. It doesn't say they have to also release any magic spells they use to compile it. Actually, it *does*. If the code was released with missing 'magic fairy dust' required to actually compile the GPL derived binaries they release, they would be in violation of GPL2 section 3. You should read http://gpl-violations.org/faq/sourcecode-faq.html to understand the implications of the GPL on source code release. You want to read the sections on 'What are scripts used to control compilation?' and 'What are scripts used to control installation?' -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Re: NameVirtualHost and CGI Problems
Mike -- EMAIL IGNORED wrote: On Thu, 09 Oct 2008 17:51:54 +0200, Ralph Angenendt wrote: [...] [...] IOW: What did you try to do? What happened? What did you expect to happen? What does your config look like? Are there any errors in the log file? Ralph [...] Indeed. Here is a summary: [...] What do you get in the error_log? -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] RAID on Email Server
Matt wrote: Right now its running pretty good but here it is. Device:rrqm/s wrqm/s r/s w/s rsec/s wsec/srkB/swkB/s avgrq-sz avgqu-sz await svctm %util sda 0.60 142.80 67.20 170.20 678.40 2292.80 339.20 1146.4012.52 118.53 615.66 4.21 99.92 You have about 3 times more writing going on than reading. RAID1 isn't going to do much for you. You might want to try four disks in a RAID10 instead. And put your mail folders and spool on partitions mounted using 'noatime'. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] HA Storage Cookbook?
Steve Thompson wrote: On Fri, 7 Nov 2008, Gordon McLellan wrote: I meant SAS; specifically Seagate Barracuda ES.2 drives. Here's a tiny version of their huge url: http://tiny.cc/3X9fI No, they are not the super fast and expensive 15krpm database drives. Indeed. They're not SAS either. From the manufacturer's page: Barracuda ES.2 SAS 3.0-Gb/s 1-TB Hard Drive Sure sounds like SAS to me. What leads you to believe they are not being truthful? -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] [OT] stable algorithm with complexity O(n)
David Hláčik wrote: Well, something with linear complexity O(n) which i have to prove, Merge sort, Insertion sort or selection sort does not have O(n) complexity. I believe that something like RadixSort, CountingSort, BucketSort altought i am not sure I'm not especially inclined to do someone's homework for them. But since you asked for a hint...My mathematical intuition suggests starting by mapping the data into an array of n buckets where each bucket is determined by the integer part of the square root of each number in the dataset. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] [OT] stable algorithm with complexity O(n)
Marko Vojinovic wrote: [...] Basically, count the number of appearances of every number in your set. If you have a set a priori bounded from above and below --- which you do, [1, n^2] --- you first allocate an array of integers of length n^2. By definition, your proposed algorithm is O(n^2), not O(n). ;) -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] [OT] stable algorithm with complexity O(n)
Nicolas Thierry-Mieg wrote: Jerry Franz wrote: Marko Vojinovic wrote: [...] Basically, count the number of appearances of every number in your set. If you have a set a priori bounded from above and below --- which you do, [1, n^2] --- you first allocate an array of integers of length n^2. By definition, your proposed algorithm is O(n^2), not O(n). No it isn't, it's O(n) in time. O(n^2) in memory but that wasn't the question, right? Look closer at it. [...] you first allocate an array of integers of length n^2. Set all elements to zero, [...] go through the whole set from 1 to n^2, and if the value of k-th element is nonzero, print number k appropriate number of times. [...] O(n^2) operations are required. It is O(n^2) both in time and memory as described. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] [OT] stable algorithm with complexity O(n)
Marko Vojinovic wrote: On Sunday 14 December 2008 03:33, Jerry Franz wrote: [...] By definition, your proposed algorithm is O(n^2), not O(n). ;) Oh, you mean because the upper bound is n^2, right? Sure, of course, this particular case is O(n^2). Your proposal in your other post with the square roots would probably improve that in this case. However, I was just giving the OP a hint in the general direction of a typical O(n) algorithm, didn't have an intention to provide a full working solution for his specific case. It's his homework, not mine. ;-) Fair enough. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] can't install rrdtool, problems with dependancies
Kai Schaetzl wrote: Jim Perrin wrote on Sat, 24 Jan 2009 08:47:43 -0500: or packaging oversite in rpmforge no, I know it works. I just installed it from rpmforge using 'yum install rrdtool' with no problems. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] CentOS/SNMP update breaks MRTG?
Noob Centos Admin wrote: I got itchy fingers over the weekend and decided to fix what wasn't broken and upgraded one of the older servers from Centos 5.2 to Centos 5.3. Following the recommended process of updating glibc and such before the rest, it appeared to work perfectly and rebooted without problem. [...] Did anybody else have similar experiences with MRTG failing after the update and what was the simple fix? It does not make any sense that I have to jump through so much hoops to get just the default functionality back. Thus I believe there must be one small thing I'm overlooking. Check the snmpd.options file (it can be at either /etc/snmpd/snmpd.options or /etc/sysconfig/snmpd.options depending on your system history). When I upgraded to 5.3 I found that it broke the options I was using to suppress logging of the SNMP polling. A set of options that work are OPTIONS=-Ln -Lf /dev/null -p /var/run/snmpd.pid -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] looking for RAID 1+0 setup instructions?
Rudi Ahlers wrote: Hi Oliver, It's not the same thing :) Although they work, and do the same, the installer CD mdadm needs to support it. The specific appliance that I want to install, doesn't support RAID 10, so I need to install RAID 1 + RAID 0, i.e. setting 2x RAID 1 mirrors, and then stripe then in RAID0 - but once the first 1 mirrors are setup, I can't stripe them. I've seen people use LVM to add them to one volume, but the installer doesn't see to like that either Hmmm... 'specific appliance'. This doesn't sound like you are installing CentOS. This makes it *really* hard for us to help you since we have absolutely no idea what you are actually doing. ;) A) What are you actually doing? B) Do you have to have RAID10 during install or is it sufficient that you can build a data 'drive' after install? -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] SSL and virtual hosts?
Tracy Phillips wrote: 1) Use a wildcard cert. You can use *.somedomain certs to serve multiple SSL domains on a single IP so long as they fit in the *.somedomain pattern. This is incorrect. apache can't read the headers since the traffic is encrypted. If it can't read headers, it does not know which vhost to use and thus can not serve up the correct files If you have more than one ssl vhost, you will have to use two IP's. You can use one SSL vhost with many non SSL vhosts on the same IP with no issues. Yes you can. I have SSL servers configured precisely like that. They work fine. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] smartd and 3ware 9xxx configs
Jim Perrin wrote: I'm looking to do a bit more monitoring of my 3ware 9550 with smartd, and wanted to see what others were doing with smart for monitoring 3ware hardware. Do you have the smartd.conf configured to test, or simply monitor health status? Are you monitoring the drive as centos sees it (/dev/sdX) or are you using the 3ware /dev/twaX for monitoring? Opinions and discussions are welcome :-P I run smart tests weekly in a staggered fashion during off hours on my 3ware arrays. Like this: /dev/twa0 -d 3ware,0 -H -l selftest -l error -o on -S on -s (O/../../1/18|S/../../2/22|L/../../3/01) -m root /dev/twa0 -d 3ware,1 -H -l selftest -l error -o on -S on -s (O/../../2/18|S/../../3/22|L/../../4/01) -m root I've found that the smart monitors are pretty good about giving me at least some warning about imminent drive failures when I do this. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] 4 X 500 gb drives - best software raid config for a backup
dnk wrote: Hi there, I am currently setting up a server that will house my backups (simply using rsync). This system has 4 X 500 gb drives and I am looking to raid for max drive space and data safety. Performance is not so much a concern. My experience with software raids in nil, so some of these may seem like pretty dumb questions. I was thinking a raid 1 is probably sufficient. Would it be best to raid 1 two drives each and LVM them together? The configuration you want is a hybrid of RAID1 and RAID5. The RAID1 is because GRUB doesn't grok RAID5, but is OK with just your /boot partition in RAID1. Make a RAID1 for your /boot partition as follows: /dev/md0 - /dev/sda1, /dev/sdb1, /dev/sdc1 (S), /dev/sdd1 (S) (100 Mbytes) Make a RAID5 as follows for a LVM partition using the rest of your available space as follows (just under 1500 Mbytes): /dev/md1 - /dev/sda2, /dev/sdb2, /dev/sdc2, /dev/sdd2 Create a LVM partition on /dev/md1 and carve out your / and swap partitions from it. My next question would be about how to do this as I have never done a linux software raid. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] 4 X 500 gb drives - best software raid config for a
Benjamin Franz wrote: Make a RAID5 as follows for a LVM partition using the rest of your available space as follows (just under 1500 Mbytes): Sorry. Typo. Just under 1500 Gbytes. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] 32 or 64 bit (4 gb ram)
Paul Hussein wrote: there still doesnt seem to be a 64bit java plugin You can use the 32bit plugin if you change the launcher script to launch the 32 bit version of firefox instead of the 64 bit version. On Tue, Mar 3, 2009 at 11:15 PM, Florin Andrei flo...@andrei.myip.org mailto:flo...@andrei.myip.org wrote: Dnk wrote: Is there any real advantage to using 64 bit when I am right at the 4gb ram threshhold? Nice plans to add more ram. The machine will just be a backup machie (rsync). For a server type of thing, 64 bit is usually perfect. 32 bit is sometimes a better deal on desktops, but even there the situation is changing. Maybe this year I'll use 64 bit on my desktop(s) for the first time, as it seems most of the lingering problems are being solved, finally. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] ssh - alternate ports, and host verification
dnk wrote: I have a centos box that will need to ssh into 2 other centos boxes (with keys). Now one of these boxes is a firewall, and another is a system behind the firewall. I have rules in my firewall to punch into the system behind the FW. Now if i connect to the IP (sine the public one is shared), anytime i connect to the other system, I get the host verification failed error and have to remove the IP from the known_hosts file. What is the best (secure) way to get around this? I know i can disable the check, but that is not my preferred way. There are two ways to do it. The first way is to simply set the host keys to be the same on all the boxes (copy the contents of the /etc/ssh/*key* files from one box to all of the boxes). The other way is to setup separate ssh_config files for each destination with different known_host files and invoke ssh as 'ssh -F configfile1 host1', 'ssh -F configfile2 host2', etc. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] OT Question about raid 5
Per Qvindesland wrote: Hi List I am hoping that someone here could perhaps give me a straight answer on a question that someone asked me today I have always belived that if you have 5 hard drives 1 50gb second 50gb third 20gb fourth 60gb firth 30gb that the largest would then be the size of the smallest disk, not 80 or 100 or 120 for that matter or am I wrong here In general you are correct for simple 'out of the box' type configurations and for most hardware RAID controllers. But there are advanced tricks that can be played with 'hybrid' RAID levels that can achieve larger sizes from smaller drives. For your example drives of 2 x 50GB, 1 x 20GB, 1 x 60GB, and 1 x 30GB, using software RAID, you could use use linear mode to make one 50GB 'drive' out of the 30GB and the 20GB and then make a RAID5 out of the 2 X 50GB the 1 X 60GB and the 'fake' 1 x 50GB resulting in a RAID5 with 150GB available vs a naive 'just bang them together' as a 5 x 20GB RAID5 approach which would only give you 80GB. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] OT: looking for a rsync equivalent for Windows platforms
Rudi Ahlers wrote: Hi all, Does anyone know of a good free rsync type program for Windows platforms? Like most of us, I need to work on both Windows Linux environments, and would like to sync some data (music, videos, photos, documents, thunderbird profiles, FF bookmarks, etc) between a USB HDD, my Linux (CentOS + KDE) PC, and Windows Laptop at the office. [...] SyncToy works well for me. http://en.wikipedia.org/wiki/SyncToy -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] 40TB File System Recommendations
On 04/15/2011 06:05 AM, Christopher Chan wrote: Woohoo, next we will be seeing md raid6 also giving comparable results if that is the case. I am not the only person on this list that thinks cache is king for raid5/6 on hardware raid boards and the using hardware raid + bbu cache for better performance one of the two reasons why we don't do md raid5/6. That *is* md RAID6. Sorry I didn't make that clear. I don't use anyone's hardware RAID6 right now because I haven't found a board so far that was as fast as using md. I get better performance from even a BBU backed 95X series 3ware board by using it to serve the drives as JBOD and then using md to do the actual raid. Yeah, you are right - but cache is primarily to buffer the writes for performance. Why else go through the expense of getting bbu cache? So what happens when you tweak bonnie a bit? For smaller writes. When writes *do* fit in the cache you get a big bump. As I said: Helps some cases, not all cases. BBU backed cache helps if you have lots of small writes. Not so much if you are writing gigabytes of stuff more sequentially. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
[CentOS] A Group is Its Own Worst Enemy (was: EL 6 rollout strategies? (Scientific Linux))
On 05/17/2011 03:06 AM, John Doe wrote: Maybe all the non-technical discussions could go into a CentOS Politics/Philosophy new list...? And on that note, some required reading for everyone in this floating flame war. Don't skim it - read it. http://www.shirky.com/writings/group_enemy.html -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Feed a list of filenames to vim
On 05/18/2011 08:06 AM, Benjamin Franz wrote: On 05/17/2011 09:19 AM, Jussi Hirvi wrote: There are some googlable ways to feed a list of filenames to vim, but I stumble on weird results. [...] The easy way for me is 'avoid the shell - use Perl instead': perl -e 'my @files = grep(!/^\s*$/,ARGV); chomp @files; system(vim,@files);' example_list.txt Quick change to handle filenames that start with '-' as well: perl -e 'my @files = grep(!/^\s*$/,ARGV); chomp @files; system(vim,--,@files);' example_list.txt -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] SSD for Centos SWAP /tmp /var/ partition
On 05/23/2011 09:39 AM, Gordon Messmer wrote: On 05/23/2011 02:31 AM, Kevin Thorpe wrote: Just be aware that SSDs wear out. They have a limited number of write cycles. Nowadays they all do 'wear levelling' to even the writes across the drive but even so they don't last very long in heavy write usage. Yes, there's a limit number of writes. With wear leveling you should be able to write to the drive at its full rate, constantly, for years before you actually wear out the drive. However, SSD drive reliability itself has been very poor in the field. The failure rate is obscene. See Jeff Atwood's 'The Hot/Crazy Solid State Drive Scale': URL:http://www.codinghorror.com/blog/2011/05/the-hot-crazy-solid-state-drive-scale.html -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] SSD for Centos SWAP /tmp /var/ partition
On 05/23/2011 11:01 AM, Rudi Ahlers wrote: Now, the question is, is is there any way to tell EXT3/4 to use a separate drive as a cache drive for the same purpose? OR, how about telling CentOS to use a separate drive for caching purposes in the same way? You can use an external journal on a SSD to speed up at least writes by quite a lot. http://insights.oetiker.ch/linux/external-journal-on-ssd/ But, for paranoia's sake, I would RAID1 the SSD with a second SSD. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Vim scripting - cursor motion
On 06/09/2011 08:37 AM, Les Mikesell wrote: I'd highly recommend perl for this because it can also do the SQL part directly via DBI without all of the intermediate contortions you'll have to do in files otherwise. It should take about half a page of your own code to connect to the DB, read the file, transform it line-by-line to sql and execute the sql statements. And unlike other approaches with a pipeline of different tools, you can generate sensible error messages in the right places that have something to do with the input. *AND* by using prepared statements in Perl you don't have to worry about escaping the text to prevent accidental SQL injections. It is all handled for you. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] CentOS-6 Status updates
On 06/14/2011 08:41 AM, m.r...@5-cent.us wrote: Yeah, but some people appear to think (or at least that was what I got from the post of the guy I was replying to) that fedora is good enough for production. *blink* Absolutely not. I was talking about Ubuntu Server LTS. I don't use Fedora for *anything*. I gave up on it back around FC5. Ubuntu Server LTS is *very* suitable for production use. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Software Protection on centos
On 05/03/2010 04:50 AM, premr...@digilink.in wrote: Hi, I would like to have a software protection for my hardisk. I have some query regarding that (1) In Centos, is it possible to do a hardisk protection. Ex : Even if the hardisk is taken from a PC and used on another PC, it should not be executable. (2) Also if the entire binary of the source is mounted on a partition say /tmp, is it possible to make that mount point as protected, visible only after entering a password or similar to that. I would look at TrueCrypt. http://www.truecrypt.org/ -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Benchmark Disk IO
On 05/19/2010 06:14 AM, John Doe wrote: From: Matt Keatingkeats...@gmail.com I don't usually use iozone (I usually use bonnie++) so take this with a grain of salt, but those speed look suspiciously like cache speeds. Bump the size (-s parameter) up to twice your real RAM size. Will give that a try - 16gb file incoming Or maybe do a: sync; echo 3 /proc/sys/vm/drop_caches between the 2 tests...? It wouldn't help. The problem is the tests were using file sizes small enough to easily fit completely into the system caches. So you end up benchmarking the performance of the I/O system caches - not the drives themselves. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Odd failure of smbd to start from init.d - CentOS 5.4
On 05/20/2010 04:46 PM, Whit Blauvelt wrote: Also, since sh /etc/init.d/smb (re)start works but /etc/init.d/smb (re)start doesn't, I can't see how the difference between those two invocations would change the handling of the lock files. It's still the same script being run. Just some change in the environment whose subtlety escapes me. I would start by comparing the values of all the environment variables between running as /bin/sh and /bin/bash: env bash_env.txt /bin/sh env sh_env.txt exit diff bash_env.txt sh_env.txt -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Odd failure of smbd to start from init.d - CentOS 5.4
On 05/25/2010 04:11 PM, Whit Blauvelt wrote: Hi Brian, I've been all over the environment comparisons before, I think. The question currently is: What can be the difference between /home/smb restart - which works, and /etc/init.d/smb restart - which fails when a diff between the two smb files shows no difference? Are you running with SELinux on? -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Odd failure of smbd to start from init.d - CentOS 5.4 - it's that fine SELinux
On 05/26/2010 08:23 PM, Gordon Messmer wrote: On 05/26/2010 08:44 AM, Benjamin Franz wrote: [...] The *theoretical* system security improvement of SELinux is trumped by the *practical* observation that I have had existing systems broken by SELinux multiple times on the mere handful of systems I have run it on in enforcing mode, but have yet to see a single one of several dozen (all internet exposed) up-to-date *non*-SELinux systems hacked. You are comparing two unlike things. You can't very well judge the benefits of SELinux based on a system which hasn't needed its protection. I'm comparing a simple metric that applies to *ANY* system admin job: (Downtime) / (Machines * Years) The metric *DOESN'T CARE* if that downtime is because of bad power, hard drive crashes, hackers, cosmic rays, SELinux, or poor admining. It cares that the services are offline, on how many machines and for how long. Arguing that I'm comparing apple and oranges is like claiming that (using my analogy of faulty air bags again) it isn't *meaningful* for me to say that faulty airbags that go off randomly while driving is a bigger hazard than car accidents for me because I haven't had any car crashes specifically needing air bags: The airbag going off randomly while I'm driving is very likely to *cause* a serious car accident itself. I'm measuring *all* serious accidents - not just 'accidents where the airbag might have gone off'. A 'safety feature' that *causes* more damage than it prevents isn't a safety feature - it's a hazard. And on otherwise properly maintained systems, SELinux is a hazard. It is a 'safety' feature that is in practice more dangerous to system stability than what it is trying to fix. I advise administrators to test all updates on non-production systems. SELinux updates are no exception. __ I have *twenty* virtual machines I deploy updates to before it ever touches my production systems. Not everything is testable on non-production machines. Nor, as the system admin, senior programmer and desktop support person for the entire company do I have the sheer time needed to test every sub-system before deployment. And I shouldn't damn well *need* to on a normal system update to an Enterprise grade distribution (I'm not knocking the CentOS team here - this is about Redhat and SELinux). SELinux makes my systems significantly *LESS* reliable instead of *MORE* reliable. And that is a bad thing. Now back to fixing the SELinux configuration on a machine I had to put in 'permissive' mode a few weeks ago because the last round of SELinux updates broke the web server's ability to open its own log files. That is what I still have left to fix after having to relabel the entire system to fix the other breakages the update introduced. And no - I'm not kidding or making things up. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Odd failure of smbd to start from init.d - CentOS 5.4 - it's that fine SELinux
On 05/27/2010 08:51 AM, Gordon Messmer wrote: On 05/27/2010 05:55 AM, Jerry Franz wrote: I have *twenty* virtual machines I deploy updates to before it ever touches my production systems. Not everything is testable on non-production machines. ... Now back to fixing the SELinux configuration on a machine I had to put in 'permissive' mode a few weeks ago because the last round of SELinux updates broke the web server's ability to open its own log files. That sounds like the sort of thing that you'd have noticed if you'd applied the update and started the service on a test host before production. I have finite resources. If I had junior admins who could spend weeks doing testing of every update before deployment, twice as many physical machines as I now have so I could deploy dozens of VMs _just for testing updates_ (and let's not even begin to discuss the non-virtualizable machines such as the backups storage servers) , an extra co-location rack to put those additional servers in, and the budget to fix any emergent SELinux breakage, then, yeah, that would work. At a net cost several times higher than my current budget. Or I can turn off SELinux on most of my systems and not get my systems gratuitously broken every few to several months by SELinux policy updates. For my current budget. Hmmm What to do... What to do -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] PHP file upload limit
On 06/09/2010 12:32 PM, Boris Epstein wrote: Eero, I've got 4 GB of swap. At the moment all 4 GB less 100 MB of it is available. That logically should be enough to allow me to upload a 2 GB file, I would think. Looking at the bugtracker: http://bugs.centos.org/view.php?id=3118 PHP is not built with large file support on 32 bit x86, probably other 32 bit platforms, all releases of CentOS 4 Additional Information I verified that upstream does not have this problem. It is severe enough for my use (scientific processing) that I am changing OS. While the report is for CentOS4, it may be related to your problem. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization as cheap redundancy option?
On 6/25/2010 7:33 AM, Brian Mathis wrote: On Fri, Jun 25, 2010 at 9:04 AM, Emmanuel Noobadmin centos.ad...@gmail.com wrote: I'm wondering if virtualization could be used as a cheap redundancy solution for situations which can tolerate a certain amount of downtime. Current recommendations is to run some kind of replication server such as DRBD. The problem here is cost if there are more than one server (or servers running on different OS) to be backed up. I'd basically need to tell my client they need to buy say 2X machines instead of just X. Not really attractive :D So I'm wondering if it would be a good, or likely stupid idea, to run X CentOS machines with VMware. Each running a single instance of CentOS and in at least one case of Windows for MSSQL. Sure. I run 4 machines with VMware Server2 in production. Three with the live VM machines and a 4th with live 'near-mirror' VMs of all the others. So if any of the machines physically fails for whatever reasons not related to disk. I'll just transfer the disk to one of the surviving server or a cold standby and have things running again within say 30~60 minutes needed to check the filesystem, then mount and copy the image. I don't like this so much. It means you physically have to move something, possibly have to fsck the drives and deal with potential corruption of the VM images. I thought I could also rsync the images so that Server 1 backs up Server 2 image file and Server 2 backs up Server 3 etc in a round robin fashion to make this even faster. But reading up indicates that rsync would attempt to mirror the whole 60gb or 80gb image on any change. Bad idea. You have multiple choices here. I do three things: 1) I have 'near'-image machines running live all the time that rsync all the production relevant portions of the live machines once a day. With scripts that can put them live in a few seconds or minutes at need. 2) I have snapshots of the VM images themselves that I take once a week by shutting down the VMs, taking an LVM static snapshot, restarting the VMs, rsyncing the snapshot to another machine, and then removing the snapshot. Since rsync only transfers the *changed* part of the image files this only takes a few hours for some hundreds of gigabytes of VM images and only has a few minutes of actual downtime. Since VMware Server 2 has an unfixed 'cpu load' leak requiring you to stop/restart the machines about once every week or two anyway, it kills two birds with one stone. 3) I also have inside-the-vm full rsync-over-ssh with hardlinking onsite/offsite backup of all the live virtual machines taken daily with a 7 x daily, 4 x weekly, 3 x monthly, 2 x quarterly, 2 x semi-annual retention. So while this is not real time HA but in most situations, they can tolerate an hour's downtime. The cost of the redundancy also stays constant no matter how many servers are added to the operation. Any comments on this or is it like just plain stupid because there are better options that are equally cost effective? This is one of the advantages of using VMs, and I'm sure most people are using it for this reason in one way or another. However, there are a few things you need to worry about: - When the host crashes, the guests will also, so you'll be in a recovery situation just like for a physical crash. This is manageable and something you'd have to deal with either way. I'm not so hot on the 'move the physical disk' idea. 'Move the data' seems better to me. - Rsyncing the VMs while they are running leaves them in an inconsistent state. This state may or may not be worse than a simple crash situation. One way I have been getting around this is by creating a snapshot of the VM before performing the rsync, and when bringing up the copy after a crash, revert to the snapshot. That will at least give you consistent filesystem and memory state, but could cause issues with network connections. I usually reboot the VM cleanly after reverting to the snapshot. Note - *take the snapshot while the vm's are 'stopped' or 'paused'* :) Rsync will not transfer the entire file when transferring over the network. It scans the whole thing and only sends changes. If you have --progress enabled it will appear to go through the whole file, but you will see the speedup go much higher than a regular transfer. However, sometimes this process can take more time than doing a full copy on a local network. Rsync is meant to conserve bandwidth, not necessarily time. Also, I suggest the you use a GB network if you have the option. If not you could directly link the network ports on 2 servers and copy straight from 1 to the other. Yep. If you are looking at VMware Server for this, here are some tips: - For best performance, search around for vmware tmpfs. It will dramatically increase the performance of the VMs at the expense of some memory. +1 We are talking an order of magnitude
Re: [CentOS] Redundant LAN routing possible?
On 7/10/2010 2:21 PM, Emmanuel Noobadmin wrote: I've been reading that it's possible to set up a system with multiple NIC to provide redundant internet connectivity such that it will switch to a secondary connection if the primary ISP fails. Is it possible in a similar way to setup redundant LAN routing? I read that it is possible to aggregate/bond multiple NIC to stackable switches that support link aggregation and redundancy. But if only simple switches are available, is something like this possible? e.g. System A eth0 - lan switch/router 1 eth1 - lan switch/router 2 System B eth0 - lan switch 1 eth1 - lan switch 2 Then somehow specify that, if lan switch 1 fails, the two systems will switch to using switch 2 so that in case of a switch failure, the network continues to remain operational. Yes. You can do it. I've done it before. All you need is the right choice of bonding mode . You set up bond0 for eth0 and eth1 and it 'just works'. To make it more robust, cross-connect the two switches as well. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Redundant LAN routing possible?
On 07/10/2010 09:48 PM, Emmanuel Noobadmin wrote: Thanks for the suggestion, I'll read up more about them. The bond0 and just works sounds simple which is a Good Thing! The problem was the last time I tried to cross connect multiple switches, everything just died so there must be something a bit more involved? :D Not really. You should connect the 'uplink' port to a regular port or use a cross-over cable to connect switches (assuming your switches don't auto-switch ports) and make only one connection between each switch and the next. I've got four switches chained here in my house right now without a problem to distribute my internet connection around various rooms using cheap retail 5 port d-link switches. Just don't create loops or other weird architectures, don't chain too many together, and you should be fine. In the mean time since my post, I came across STP (spanning tree protocol) that seems to be designed to handle this sort of thing, i.e. figure out the shortest path and prevent network shortcircuit like what I had experienced with cross connecting multiple switches. But it apparently takes 50 seconds to reconfigure anytime sometime in the circuit fails. There is supposedly a Rapid STP that only takes 3 seconds. Several couple-of-years old search results indicate that it was tested in 2.4 kernel and will be in 2.6 kernel. However, I cannot seem to find anything newer that confirms if such functionality is really in the current kernel. Anybody has any idea? You probably don't need to worry about STP unless you are using explicitly bridging the servers' NICs. And hopefully your hardware is reliable enough that worrying about a 50 second reconfiguration is something that happens once in several years in the first place. -- Jerry Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Desktop Supercomputer
On 7/17/2010 2:11 AM, Rajagopal Swaminathan wrote: Q. If I can compute in cloud, in which cloud can I supercompute at an affordable or sponsored cost? I may be a gamer, AE student, Graphic designer, renderer and so forth. Now which part of above you did not understand? sigh... how I hate my (in)ability to communicate tech to people inspite of having been kindly classified as a lightweight fossil in this list? Why elders are made to shout when they don't want to? Everything you listed is interactive realtime or near-realtime graphics intensive. A cloud is not really suited to that kind of task to begin with. And you appear to be additionally attempting to find out if you could use an *existing* cloud (for example Amazon EC2) to do it - meaning not only are you talking about an architecture that isn't really suited to the problem, you are talking about putting it behind *SLOW* network connections to boot. Never-mind how *fast* a cloud is (or is not), you can't move the rendered bits back and forth to a desktop over a remote network connection at any kind of sane speed. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] ext4?
On 08/07/2010 11:05 AM, Benjamin Franz wrote: On 08/07/2010 10:55 AM, James Bensley wrote: On 7 August 2010 17:41, Laurent Wandrebeckl.wandreb...@gmail.com wrote: so a mount -t ext4 should work, as kernel-2.6.18-194.8.1.el5 provides /lib/modules/2.6.18-194.8.1.el5/kernel/fs/ext4/ext4.ko. This is probably going ot provide the answer (to you atleast, its not so clear to me); `uname -r` tells me I'm on kernel 2.6.18-92.el5. Within /lib/modules/2.6.18-92.el5/kernel/fs/ thers is no ext4, but I have do have a /lib/modules/2.6.18-194.8.1.el5 folder and in there is kernel/fs/ext4/ext4.ko so a newer kernel is preset with the required module but its not active, or something? I'm going to say I need to recompile my kernel and include the module since its present on my box or work out why the newer kernel files are present but not in use? You are *WAY* behind on your running kernel. Check /boot/grub/grub.cfg and, assuming you have the more recent kernels installed, change it to default to the current kernel and reboot. Alternatively, if you don't want to edit grub.cfg just yet, reboot and *choose* the most current kernel from the grub boot menu to test it. I use ext4 all the time and don't have any problems with it. Correction: I forgot that on CentOS you want /boot/grub/grub.conf instead. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Ethernet Quad
On 08/12/2010 05:56 AM, Daniel Bruno wrote: Hello, Someone can indicate some Ethernet device Quad 10/100 to use with CentOS 5.x? I don't know about 10/100. For 10/100/1000 I use Intel quad port boards. They work fine. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] tar - ssh - standard out
On 08/12/2010 05:33 AM, Les Mikesell wrote: Why do you need any other process involved to work with a data stream? If you want to collect it to a remote file, you can | ssh remotehost 'cat path_to_file'. Just be sure to quote the redirection so it happens on the remote side. At a guess it's the compression he is after. Over a slow link it could make a substantial difference. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Ethernet Quad
On 08/12/2010 06:06 AM, Rudi Ahlers wrote: On Thu, Aug 12, 2010 at 3:01 PM, Jerry Franzjfr...@freerun.com wrote: On 08/12/2010 05:56 AM, Daniel Bruno wrote: Someone can indicate some Ethernet device Quad 10/100 to use with CentOS 5.x I don't know about 10/100. For 10/100/1000 I use Intel quad port boards. They work fine. Sorry to hijack this thread, but it could be relevant. As matter of interest, do these cards offer lower throughput than 4x single 1GB cards? Depends mostly on if you are using PCI/PCI-X vs PCI-express. At high bit rates you can saturate the old PCI bus. A single gigabit port can pretty much saturate a 32-bit PCI bus at 33MHz. PCI-express can go a lot faster. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Date drift and ntpd
On 8/12/2010 8:03 PM, Les Mikesell wrote: Warren Young wrote: The strategy I recommended is based on the fact that its worst case behavior (a small negative jump every hour) is not a problem for me. If it is a problem for your application, you need a different design. It's a bad idea in the general case. If you have scheduled jobs, ntpdate may jump the clock enough to miss the trigger or run them twice, where ntpd always tries to move the clock fractional seconds at a time so as not to let that happen. Plus, ntpdate does no sanity check at all - if the clock source is badly off, the client will follow blindly even if it goes to the wrong century. Whereas ntpd will simply quietly fail to sync at all if it is more than a few minutes off. ;) I've used ntpdate to keep exceptionally balky machines in phase before. If you do it frequently enough that the jump is never more than a second or two it works fine as long as you can tolerate the occasional out of order timestamp. Cron is sensitive only to the minute level and if you are paranoid about it, sync it at an odd time (something like 47 minutes after the hour) that just won't conflict with other cronjobs. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] best ways to do mysql backup
On 08/14/2010 03:58 PM, John Hinton wrote: For uninterrupted delivery of dynamic content from the database... or no downtime, replication to a slave is the way to go. This is 'sort of' a T-ing effect, except it is to another database. That slave database however can be stopped, a mysgldump done to a backup and then restarted, at which point the replication restarts and the slave database is updated to match the master database. It works really well without huge overhead increases. Google MySQL replication for lots of info about setting it up. I didn't include this since the OP specified _other_ than tar, replication and mysqldump. But the most efficient and lowest downtime is to combine replication with the LVM snapshot and rsync. Since the OP specified he has around 100 GB of data, rsyncing the snapshotted data directory will be substantially more efficient than using mysqldump for transfer to the remote system (assuming he doesn't churn most of the contents of the database between syncs). -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] how long to reboot server ?
On 09/03/2010 02:15 PM, Ross Walker wrote: This is good info! What I am wondering is if there is a way to prevent new kernels from becoming the default by... default? That way one won't be pleasantly surprised that after a long uptime and several updates, that on the next reboot their applications stop working because of a kernel update that hadn't been tested yet. A way where the admin must manually choose the default kernel. Look at /etc/sysconfig/kernel -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] OT: linux desktop market share more than 1%
On 10/08/2010 03:25 PM, Warren Young wrote: On 10/8/2010 4:09 PM, m.r...@5-cent.us wrote: But OS X can legally only run on Apple (tm$$$) systems, where Linux can run on *anything* and anybody's inexpensive hardware. Apple hardware is fairly priced when compared on quality. Yes, there are cheap POS PCs that compare favorably on features with Apple hardware at a lower cost. I've used many such. They often break more readily, or fail to satisfy on some other level. There's more to a PC than spec list. [snip] Apple runs commodity hardware that is essentially identical to everyone else's - just priced 3X more. Hardware quality **IS NOT** the difference between a Mac and everyone else. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] the wandering MAC?
On 10/13/2010 1:11 PM, Les Mikesell wrote: But the ifcfg-ethX scripts don't run if the HWADDR entry doesn't match the NIC MAC. How do you get the right name connected to the right nic so you can even run ifconfig sensibly? You don't *have* to use HWADDR in the ifcfg-* file. Just comment it out on the NIC that is having problems. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] FYI: Red Hat Enterprise Linux 6 Release Candidate Available to Partners
On 10/19/2010 04:10 AM, Nicolas Thierry-Mieg wrote: Benjamin Franz wrote: Yes, to partners :) I'm pretty sure Deyan is referring to their GPL obligations to make the source code available for most of it. GPL doesn't say you have to distribute source code to the whole world, only to people you distribute the binaries to (ie the partners here). Clauses 2b and 3b of GPLv2 would appear to say otherwise.* 2b)* You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License. *3b)* Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; any third party and all third parties not the third party. It is a subtle but important distinction. It means you can't be *selective* about who gets it as I read it. Everyone or no one are your options. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] FYI: Red Hat Enterprise Linux 6 Release Candidate Available to Partners
On 10/19/2010 04:16 AM, Karanbir Singh wrote: hi Guys, On 10/19/2010 12:00 PM, Benjamin Franz wrote: I'm pretty sure Deyan is referring to their GPL obligations to make the source code available for most of it. .. this has nothing to do with it... Yes, it does. http://www.softwarefreedom.org/resources/2008/compliance-guide.html Second, note that the last line makes the offer valid to anyone who requests the source. This is because v2 § 3(b) requires that offers be “to give any third party” a copy of the Corresponding Source. GPLv3 has a similar requirement, stating that an offer must be valid for “anyone who possesses the object code”. These requirements indicated in v2 § 3(c) and v3 § 6(c) are so that non-commercial redistributors may pass these offers along with their distributions. Therefore, the offers must be valid not only to your customers, but also to anyone who received a copy of the binaries from them. Many distributors overlook this requirement and assume that they are only required to fulfill a request from their direct customers. Once you publish/distribute GPL licensed code to *anyone*, your obligation to provide source kicks in for *everyone*. In practice, few people hammer at a company in process over it. But you *can*. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] FYI: Red Hat Enterprise Linux 6 Release Candidate Available to Partners
On 10/19/2010 05:03 AM, Karanbir Singh wrote: On 10/19/2010 12:52 PM, Jerry Franz wrote: Once you publish/distribute GPL licensed code to *anyone*, your obligation to provide source kicks in for *everyone*. In practice, few people hammer at a company in process over it. But you *can*. I am not a lawyer, but you blurb seems to indicate that the issue is applicable to people with the object code, which would make my last point valid. Only on v3 license code. Most code is still under v2. Also, there are legalise around exactly what is considered a product / code snippet / build script and distribution - which is what makes things like NDA's workable. Actually, the GPL forbids using 'add on' agreements like NDAs that attempt to make it so an end user can't recompile or redistribute the code. The authors thought of those attempts to 'end run' the GPL's obligations when they wrote it. That is why clause 4 of the v2 license (or clauses 8 and 10 of the v3 license) exists. *v2: 4.* You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. NDAs that attempt to impose *restrictions* on the GPL while still publishing/distributing to a third party can't overcome the basic legal obligations of the GPL and this is *by design*. And yes, code snippets and build scripts are covered, too. See clause 3 of the v2 license. Being as deeply involved in a FOSS exercise like CentOS as you are, you really should take the time to fully understand the license that enables it to happen at all. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] FYI: Red Hat Enterprise Linux 6 Release Candidate Available to Partners
On 10/19/2010 05:37 AM, Karanbir Singh wrote: Only on v3 license code. Most code is still under v2. and what license is the distro shipped as ? That is a very good question. The *support and subscriptions* are under RH's own license. The *code* in the packages are under the licenses of the people who wrote it (generally not RH) and range over Apache, Perl, BSD, GPL, and a few other licenses. If RH wants to *only* publish the GPL (and similarly licensed) code, they could do that. But they would have to go package-by-package and separate them out. The kernel itself is GPL v2, btw. Also, there are legalise around exactly what is considered a product / code snippet / build script and distribution - which is what makes things like NDA's workable. Actually, the GPL forbids using 'add on' agreements like NDAs that And how does the GPL get involved in relationships and partnerships that exist between people ? That is what it does. It *licenses* distribution between people. You can't say it's under GPL - but you can't redistribute it because I've made you sign an NDA. It violates the license that *you* accepted to use it yourself in the first place. RH can only use code written by other people *if they accept the license it is published under*. Otherwise *RH* itself does not have the right to use it at all. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] FYI: Red Hat Enterprise Linux 6 Release Candidate Available to Partners
On 10/19/2010 06:10 AM, mehdi wrote: how open yum.conf in mode read write 1. You need to do it as the 'root' user. Log in as 'root' and then you will be able to edit it. 2. Please don't hijack unrelated threads. To start a new topic, post a completely new message with a usefully relevant subject line. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] 6.2 - How to check for a failed disk using LVM with a hardware RAID (3ware)
On 04/05/2012 05:38 AM, Jonathan Vomacka wrote: CentOS Community, What commands can I use to check the disk health of the system when LVM2 is being used on top of a RAID 10 using a HARDWARE 3ware raid card. The OS sees a hardware raid usually as one big drive. Is there a way to check the disks individually to see if any are failing, or throwing hard or scsi transport errors? yum install smartmontools smartctl -a /dev/twa0 -d 3ware,0 You can check each drive by changing '3ware,0' to '3ware,x' where x is the drive #. You can automate the checks by configuring /etc/smartd.conf using lines like: /dev/twa0 -d 3ware,0 -H -l selftest -l error -o on -S on -s (O/../../6/22|S/../../1/2|L/../../2/1) -m r...@yourdomain.com Remember to comment out the default line (the first line of /etc/smartd.conf). -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] True bond howto for Centos 6
On 05/13/2012 10:16 AM, bob wrote: from what i get it is a problem with libvirt, using a bridge that is going through a bondon the same machine. It must be rather detailed to fix and only a few people seem to use that route. (like you and me) I've been running 14 CentOS5 VMs with bridged over active-backup bonded interfaces (actually, over three sets of bonded interfaces) on a single Ubuntu 10.04-LTS server KVM host for a couple of years now. The only real issue I have had is that during a host reboot the 'thundering herd' trying to autostart simultaneously sometimes doesn't reliably start all 14 VMs and I have to manually launch the one or two VMs that fail to launch. Also, I had to roll my own shutdown script because for whatever reason Ubuntu 10.04 thinks shooting running VMs in the head during a shutdown is a better approach than waiting for them to properly shutdown on request. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] rsyslog.conf - why the - in this entry? mail.* -/var/log/maillog
On 06/05/2012 07:30 AM, James B. Byrne wrote: In dealing with an unrelated issue I came across this in rsyslog.conf. [...] Why is there a - before /var/log/maillog? [...] A leading '-' indicates the the log is written asynchronously. It is a performance tune to keep writing the syslog from thrashing the system with syncs. See http://www.rsyslog.com/doc/rsyslog_conf_actions.html -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] problem with machine freezing for short periods
On 07/27/2012 07:23 AM, Vanhorn, Mike wrote: As a followup, I've determined that it is network related, but I'm still not sure what the problem is. I did go back to CentOS 5.2, but the problem still exists with that version, too. Basically, what seems to be happening is that the network freezes around 30 seconds, and then picks right back up. There are no errors in any logs that I can find, and process that are running locally and that only depend on local resources keep right on going and don't have a problem. I have tried using a different network card (as opposed to the one on the motherboard), but the problem happens with that, too. It almost has to be a configuration issue, or a BIOS settting, but I don't get it. That sounds like a timeout of some kind. Do you have many (thousands per minute) of transient network connections in normal operation? If so, you might be running into the open file limits if you haven't bumped up the limits. Look at /etc/security/limits.conf and try adding *- nofile 64000 -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] RAM Requirements
On 11/23/2013 07:40 AM, Fred Smith wrote: I doubt it was an actual 80386. For some years the minimum CPU requirement has been i686, which was Pentium Pro or greater. More recently the additional requirement of a CPU with PAE capabilities. I rather doubt that a processor that ran RH9 (a decade or more ago) would have PAE, though I have been wrong before (once or twice! :) :) I've got a machine that started life running RH7.3, was migrated to CentOS3 and is still running it (though hopefully not much longer - I am retiring the machine before it decides that a decade plus of service is long enough and dies on its own). The motherboard BIOS date is 05/15/2003 and the dual CPUs are 3Ghz Xeons with hyperthreading and, yes, PAE. That isn't even the oldest running system here. That honor goes to a system currently with CentOS5, a motherboard BIOS date of 03/29/2000, 384 MBytes of memory, running a Celeron 500 MHz CPU with PAE (also facing retirement in the near future). :) -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Centos 6 full backup software?
On 07/16/2014 12:50 PM, Rafał Radecki wrote: Hi All ;) I need a good tool to backup whole system on block level rather than file level and easy to use. I currently need to backup to an USB disc (50+ GB of data) a system and then reinstall it. In the future if needed I will revert to the system from backup ;) What can you recommend? I would recommend Clonezilla: http://clonezilla.org/ -- Jerry Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Convert bare partition to RAID1 / mdadm?
On 07/25/2014 03:33 PM, Benjamin Smith wrote: takes between 1 and 2 days, system load depending. We had to give up on rsync for backups in this context a while ago - we just couldn't get a daily backup more often then about 2x per week. Now we're using ZFS + send/receive to get daily backup times down into the sub 60 minutes range, and I'm just going to bite the bullet and synchronize everything at the application level over the next week. Was just looking for a shortcut... Here is an evil thought. Is this possible for you do? 1) Setup a method to obtain a RW lock for updates on the original filesystem 2) Use rsync to create a gross copy of the original (yes, it will be slightly out of phase, but stick with me for a bit) on the new filesystem on top of LVM2 on top of a RAID1 volume to make the next step much more efficient. 3) Perform the following loop: a) Set the updates lock on original filesystem b) rsync a *subset* sub-directory of the original filesystem such that you can complete it in, at worst, only a second or two c) Rename the original directory to some safe alternative (safety first)... d) Put a symlink in place of the original directory pointing to the newly synced file system sub-directory e) Release the mutex lock f) Repeat a-e until done 4) Switch over operations to the new filesystem Another approach would be to leverage something like UnionFS (see http://en.wikipedia.org/wiki/UnionFS ) to allow you to both use the filesystem *and* automatically propagate all updates to the new volume during the migration. - Jerry Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS-virt] SATA vs RAID5 vs VMware
Benjamin Franz wrote: And I just learned something new. According to http://communities.vmware.com/thread/105144;jsessionid=DE9B4FFB861971525BEDBD8984F6A670?start=15tstart=0 if you use /dev/shm for your tmpDirectory you don't pay the 'double the memory' penalty. I am testing it now. To wrap this up, VMware has actually put up a Knowledge Base entry on this documenting exactly how to do it as of last month: http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKCdocType=kcexternalId=844sliceId=2docTypeID=DT_KB_1_1dialogID=16224170stateId=1%200%2016226185 -- Benjamin Franz ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] IP based VirtualHost: IP aliases vs. additional virtual interfaces
On 08/10/2010 07:12 AM, Mathieu Baudier wrote: You don't have to restart the guest to add or remove aliases: yes I am aware of that, and that's why I'm wondering whether it is better to use aliases rather than to add virtual interfaces (which does require to restart guests with our KVM version, no hot-plug I think). You said it backwards originally. You said that aliases required restarts. ;) But is there any drawback with using aliases? Or does using virtual interfaces provide additional performance/stability/... ? I've never had issues with aliases. They 'just work'. I use hundreds of them. -- Benjamin Franz ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
