Re: [SLUG] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
jam j...@tigger.ws writes: [snip] Based on what you have said do yourself a favour and don't do LVM. LVM is a wonderful idea but it requires that you understand statistics related to disk failure and the consequences of that. This comment makes no sense to me: in what way does LVM change the risks associated with disk failure? I can't think of *anything* that is at all different in that regard. [snip] Heh. Aside from the LVM bit, this is almost certainly the best advice the OP has gotten. (Even LVM may be right; I just don't understand what James is trying to say the problem is yet. ;) From 2nd year stats (and subject to the ravages of time on my memory): a display array of 10x20 1000hour lamps will have a lamp fail on average every 20 min !! According to Seagate the failure rate of 2 disks is much greater than 2x failure rate of 1 disk http://portal.acm.org/citation.cfm?id=1090724 Along with all the cute benefits that LVM offer is a much higher disk failure rate. Is the windows-linux convert going to pay attention to needed backup regime? Ah! You are making the assumption that LVM implies multiple disks! This is absolutely not true. You /can/ use LVM to make multiple disks available in a single pool, but using it only for a single disk is also highly valuable. Also, you can use it to, for example, mirror volumes, which makes a single disk failure harmless, improving reliability. So, you are not wrong in the case you were talking about, but that is hardly the common case for LVM in the installer. I don't believe it is in the best interest of this user to do kewl rad stuff! Using basic LVM, rather than fixed partitions, on a single disk, is hardly kewl rad stuff these days. Just sayin' Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons Looking for work? Love Perl? In Melbourne, Australia? We are hiring. -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
SNIP Aside from the work mentioned above, I also edit some really big video files and do ffmpeg transformations on them. Right. In which case 64 bit is for you. So, is there some way of choosing which of the above is the best option for me? I'd suggest trying both out and see. Typically for things like graphics/video editing, I suggest 64 bit almost exclusively now because the programs are written assuming they can hold a lot of data in RAM. Adrian (Who isn't Daniel, but has hacked on a bit of PAE code in his time.) Many thanks to Daniel and Adrian who is not Daniel for the helpful pointers. Looks like a good time to try 64 bits. Cheers, Alan -- Alan L Tyreehttp://www2.austlii.edu.au/~alan Tel: 04 2748 6206 -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
On Wednesday 28 October 2009 18:37:16 slug-requ...@slug.org.au wrote: jam j...@tigger.ws writes: [snip] Based on what you have said do yourself a favour and don't do LVM. LVM is a wonderful idea but it requires that you understand statistics related to disk failure and the consequences of that. [snip] Ah! You are making the assumption that LVM implies multiple disks! I did indeed misread the original posting as 90G AND 500G disks and all of my ramblings were based on that assumption. Apologies blush James -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
[SLUG] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
I am about to upgrade a HP notebook to a larger hard disk (replace the 90Gb disk with 500Gb) and double the RAM (from 2Gb to 4Gb). In addition, to complicate matters, I would like to LVM on the larger disk to manage the linux partitions. This is the final stage of my slow move from Windows to Linux. I have the luxury of having two HP notebooks with similar but not identical hardware specifications (NC8430 and 6910p) to test various aspects of the migration (Virtual Box, video drivers for Ubuntu, etc). the current situation is that one machine has my Windows XP environment and the other my Ubuntu environment (Jaunty). I want to end up with a Windows partition and LVM managed Linux partitions on HP NC8430, 500Gb HDD, 4Gb RAM Here are the requests for advice: 1. What do I need to do to get Ubuntu to use 4Gb RAM? My current Jaunty installation only recognises around 3Gb. Is this just a kernel upgrade or 2. How complicated is it to move my linux setup from a single partition to the lvm partitions on the larger disk. My latest thought is to: a. update Ubuntu on the hard disk to match the current working environment (fix apt-get config files and/or dpkg -l on both and diff them, and them update) b. If I copy /usr and /var from the working environment to the new environment will that cause problems? (it will save re-installing some software that isn't managed by apt) c. copy /home from working environment to new disk (recommended method? rsync to new drive connected via USB?) d. use pgdump / pgrestore to move postgres databases across e. Backup new disk f. find out what doesn't work? What have I missed? Thanks, in anticipation Bill -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
On Tue, 27 Oct 2009 13:15:08 +1100 Bill Donoghoe donogh...@gmail.com wrote: I am about to upgrade a HP notebook to a larger hard disk (replace the 90Gb disk with 500Gb) and double the RAM (from 2Gb to 4Gb). In addition, to complicate matters, I would like to LVM on the larger disk to manage the linux partitions. This is the final stage of my slow move from Windows to Linux. I have the luxury of having two HP notebooks with similar but not identical hardware specifications (NC8430 and 6910p) to test various aspects of the migration (Virtual Box, video drivers for Ubuntu, etc). the current situation is that one machine has my Windows XP environment and the other my Ubuntu environment (Jaunty). I want to end up with a Windows partition and LVM managed Linux partitions on HP NC8430, 500Gb HDD, 4Gb RAM Here are the requests for advice: 1. What do I need to do to get Ubuntu to use 4Gb RAM? My current Jaunty installation only recognises around 3Gb. Is this just a kernel upgrade or I just went through this with Debian Lenny: use the bigmem kernel. Can't help much on the other questions though. Cheers, Alan 2. How complicated is it to move my linux setup from a single partition to the lvm partitions on the larger disk. My latest thought is to: a. update Ubuntu on the hard disk to match the current working environment (fix apt-get config files and/or dpkg -l on both and diff them, and them update) b. If I copy /usr and /var from the working environment to the new environment will that cause problems? (it will save re-installing some software that isn't managed by apt) c. copy /home from working environment to new disk (recommended method? rsync to new drive connected via USB?) d. use pgdump / pgrestore to move postgres databases across e. Backup new disk f. find out what doesn't work? What have I missed? Thanks, in anticipation Bill -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html -- Alan L Tyreehttp://www2.austlii.edu.au/~alan Tel: 04 2748 6206 -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
On Tue, 2009-10-27 at 13:15 +1100, Bill Donoghoe wrote: 1. What do I need to do to get Ubuntu to use 4Gb RAM? My current Jaunty installation only recognises around 3Gb. Is this just a kernel upgrade or If I remember correctly we don't support 3GB on 32-bit installs anymore - the performance overhead is terrible. AIUI you can however run a 32 bit userspace on a 64-bit kernel - but I've not done this so can't offer advise ;). There /may/ be a kernel flavour that has PAE turned on - check the server flavours. (But again, warning, slow). 2. How complicated is it to move my linux setup from a single partition to the lvm partitions on the larger disk. My latest thought is to: a. update Ubuntu on the hard disk to match the current working environment (fix apt-get config files and/or dpkg -l on both and diff them, and them update) b. If I copy /usr and /var from the working environment to the new environment will that cause problems? (it will save re-installing some software that isn't managed by apt) c. copy /home from working environment to new disk (recommended method? rsync to new drive connected via USB?) d. use pgdump / pgrestore to move postgres databases across e. Backup new disk f. find out what doesn't work? What have I missed? Sure, or you could: partition the new disk boot into readonly single user mode mount the new partitions somewhere sensible rsync everything to them. reboot -Rob signature.asc Description: This is a digitally signed message part -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
AIUI you can however run a 32 bit userspace on a 64-bit kernel - but I've not done this so can't offer advise ;). I do this all the time and it works, however the most common problem is not having all the 32 bit libraries installed, eg, glibc, where you will have the 64 bit equivalents installed on the system by default. Installing them usually presents no issue as long as the 64 bit ones are under /lib64 and 32 bit ones are under /lib. -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
On Wed, 28 Oct 2009 10:39:48 +1100 Robert Collins robe...@robertcollins.net wrote: On Tue, 2009-10-27 at 13:15 +1100, Bill Donoghoe wrote: 1. What do I need to do to get Ubuntu to use 4Gb RAM? My current Jaunty installation only recognises around 3Gb. Is this just a kernel upgrade or If I remember correctly we don't support 3GB on 32-bit installs anymore - the performance overhead is terrible. AIUI you can however run a 32 bit userspace on a 64-bit kernel - but I've not done this so can't offer advise ;). There /may/ be a kernel flavour that has PAE turned on - check the server flavours. (But again, warning, slow). al...@stormy:~/data$ uname -a Linux stormy 2.6.26-2-686-bigmem #1 SMP Sat Oct 17 18:25:48 UTC 2009 i686 GNU/Linux I haven't noticed any performance hit. Box is Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz with 4GB of memory. My stuff is mostly NOT cpu intensive, but I do an occasional compile (LyX) and LaTeX large documents. No observable change. Cheers, Alan 2. How complicated is it to move my linux setup from a single partition to the lvm partitions on the larger disk. My latest thought is to: a. update Ubuntu on the hard disk to match the current working environment (fix apt-get config files and/or dpkg -l on both and diff them, and them update) b. If I copy /usr and /var from the working environment to the new environment will that cause problems? (it will save re-installing some software that isn't managed by apt) c. copy /home from working environment to new disk (recommended method? rsync to new drive connected via USB?) d. use pgdump / pgrestore to move postgres databases across e. Backup new disk f. find out what doesn't work? What have I missed? Sure, or you could: partition the new disk boot into readonly single user mode mount the new partitions somewhere sensible rsync everything to them. reboot -Rob -- Alan L Tyreehttp://www2.austlii.edu.au/~alan Tel: 04 2748 6206 -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
On Wednesday 28 October 2009 09:00:06 slug-requ...@slug.org.au wrote: I am about to upgrade a HP notebook to a larger hard disk (replace the 90Gb disk with 500Gb) and double the RAM (from 2Gb to 4Gb). In addition, to complicate matters, I would like to LVM on the larger disk to manage the linux partitions. This is the final stage of my slow move from Windows to Linux. I have the luxury of having two HP notebooks with similar but not identical hardware specifications (NC8430 and 6910p) to test various aspects of the migration (Virtual Box, video drivers for Ubuntu, etc). the current situation is that one machine has my Windows XP environment and the other my Ubuntu environment (Jaunty). I want to end up with a Windows partition and LVM managed Linux partitions on HP NC8430, 500Gb HDD, 4Gb RAM Here are the requests for advice: 1. What do I need to do to get Ubuntu to use 4Gb RAM? My current Jaunty installation only recognises around 3Gb. Is this just a kernel upgrade or 2. How complicated is it to move my linux setup from a single partition to the lvm partitions on the larger disk. My latest thought is to: a. update Ubuntu on the hard disk to match the current working environment (fix apt-get config files and/or dpkg -l on both and diff them, and them update) b. If I copy /usr and /var from the working environment to the new environment will that cause problems? (it will save re-installing some software that isn't managed by apt) c. copy /home from working environment to new disk (recommended method? rsync to new drive connected via USB?) d. use pgdump / pgrestore to move postgres databases across e. Backup new disk f. find out what doesn't work? What have I missed? Based on what you have said do yourself a favour and don't do LVM. LVM is a wonderful idea but it requires that you understand statistics related to disk failure and the consequences of that. In your role of 'moving from windows ...' not a clever move. Over 960M of ram you need PAE memory paging with the 4G or the 64G scheme. The reasons pros and cons depend very much on your sort of applications. Until you are able to answer those questions just live with what you get and forget the extra ram beyond 3G. Transfer the OS from 1 disk to another is easy unless you've never done it smile umm hint boot on a CD and transfer not-live file systems. Heck I'd tell *my mate* to re-install, not to try to fiddle kernels to use all ram and not to contemplate LVM. James -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
Alan L Tyree a...@austlii.edu.au writes: On Wed, 28 Oct 2009 10:39:48 +1100 Robert Collins robe...@robertcollins.net wrote: On Tue, 2009-10-27 at 13:15 +1100, Bill Donoghoe wrote: 1. What do I need to do to get Ubuntu to use 4Gb RAM? My current Jaunty installation only recognises around 3Gb. Is this just a kernel upgrade or If I remember correctly we don't support 3GB on 32-bit installs anymore - the performance overhead is terrible. [...] al...@stormy:~/data$ uname -a Linux stormy 2.6.26-2-686-bigmem #1 SMP Sat Oct 17 18:25:48 UTC 2009 i686 GNU/Linux I haven't noticed any performance hit. Box is Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz with 4GB of memory. My stuff is mostly NOT cpu intensive, but I do an occasional compile (LyX) and LaTeX large documents. No observable change. It is there; the two common problems are that low memory fills, causing extra competition, and that your memory bandwidth is terribly reduced through extra TLB flushing to bounce data up above the easy line. You probably don't notice any performance hit because, frankly, almost every computer you can buy — including the one in your mobile phone — is sufficiently overpowered for the work it is asked to do[1] that you can sacrifice ten or twenty percent of performance[2] without noticing. Daniel Footnotes: [1] ...most of the time; 3D games and some science work do push the limits. Most regular desktop use doesn't. [2] Typically, this is more than running the 32-bit bigmem kernel costs. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons Looking for work? Love Perl? In Melbourne, Australia? We are hiring. -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
jam j...@tigger.ws writes: On Wednesday 28 October 2009 09:00:06 slug-requ...@slug.org.au wrote: I am about to upgrade a HP notebook to a larger hard disk (replace the 90Gb disk with 500Gb) and double the RAM (from 2Gb to 4Gb). In addition, to complicate matters, I would like to LVM on the larger disk to manage the linux partitions. That seems reasonable. [...] 1. What do I need to do to get Ubuntu to use 4Gb RAM? My current Jaunty installation only recognises around 3Gb. Is this just a kernel upgrade or It is possible that you will *never* see more than 3Gb on that hardware: some motherboards can only address 4GB of RAM, and some part of that space is needed to talk to the PCI bus, graphics card, and so forth. You may find that running another 32-bit kernel, or a 64-bit kernel, improves the situation, but you may not. That depends entirely on what your hardware supports. 2. How complicated is it to move my linux setup from a single partition to the lvm partitions on the larger disk. Using the same software? Reasonably easy. All you need to do is copy the files from the old machine into the new machine, where the new filesystem is inside an LVM container. If you want to move from 32-bit to 64-bit, though, that is harder. In that case, and perhaps generally, you are better off with a clean install on the new machine, then coping /home/myusername over. My latest thought is to: a. update Ubuntu on the hard disk to match the current working environment (fix apt-get config files and/or dpkg -l on both and diff them, and them update) *nod* b. If I copy /usr and /var from the working environment to the new environment will that cause problems? (it will save re-installing some software that isn't managed by apt) If you /just/ copy those it should go OK. A better bet is to copy the entire system wholesale, though. c. copy /home from working environment to new disk (recommended method? rsync to new drive connected via USB?) I tend to use rsync over a network connection, with a LiveCD on each machine, but *anything* that copies the files while you are not logged on is fine. d. use pgdump / pgrestore to move postgres databases across If you shut down postgresql before the move, and copy /var, the database data is already copied over. e. Backup new disk f. find out what doesn't work? What have I missed? Based on what you have said do yourself a favour and don't do LVM. LVM is a wonderful idea but it requires that you understand statistics related to disk failure and the consequences of that. This comment makes no sense to me: in what way does LVM change the risks associated with disk failure? I can't think of *anything* that is at all different in that regard. [...] Transfer the OS from 1 disk to another is easy unless you've never done it smile umm hint boot on a CD and transfer not-live file systems. Heck I'd tell *my mate* to re-install, not to try to fiddle kernels to use all ram and not to contemplate LVM. Heh. Aside from the LVM bit, this is almost certainly the best advice the OP has gotten. (Even LVM may be right; I just don't understand what James is trying to say the problem is yet. ;) FWIW, reinstalling a new 64-bit Ubuntu on the new machine, then copying your home directory and using pg_dump / pg_restore would be the easiest path. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons Looking for work? Love Perl? In Melbourne, Australia? We are hiring. -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
On Wed, Oct 28, 2009 at 12:51 PM, Daniel Pittman dan...@rimspace.netwrote: Alan L Tyree a...@austlii.edu.au writes: On Wed, 28 Oct 2009 10:39:48 +1100 Robert Collins robe...@robertcollins.net wrote: On Tue, 2009-10-27 at 13:15 +1100, Bill Donoghoe wrote: 1. What do I need to do to get Ubuntu to use 4Gb RAM? My current Jaunty installation only recognises around 3Gb. Is this just a kernel upgrade or If I remember correctly we don't support 3GB on 32-bit installs anymore - the performance overhead is terrible. [...] al...@stormy:~/data$ uname -a Linux stormy 2.6.26-2-686-bigmem #1 SMP Sat Oct 17 18:25:48 UTC 2009 i686 GNU/Linux I haven't noticed any performance hit. Box is Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz with 4GB of memory. My stuff is mostly NOT cpu intensive, but I do an occasional compile (LyX) and LaTeX large documents. No observable change. It is there; the two common problems are that low memory fills, causing extra competition, and that your memory bandwidth is terribly reduced through extra TLB flushing to bounce data up above the easy line. You probably don't notice any performance hit because, frankly, almost every computer you can buy — including the one in your mobile phone — is sufficiently overpowered for the work it is asked to do[1] that you can sacrifice ten or twenty percent of performance[2] without noticing. Daniel That's interesting, Daniel. So what are my tradeoffs. Run the normal kernel: faster but only 2.5gb; Run the bigmem kernel and suffer the performance but have more memory. Aside from the work mentioned above, I also edit some really big video files and do ffmpeg transformations on them. So, is there some way of choosing which of the above is the best option for me? Cheers, Alan Footnotes: [1] ...most of the time; 3D games and some science work do push the limits. Most regular desktop use doesn't. [2] Typically, this is more than running the 32-bit bigmem kernel costs. -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons Looking for work? Love Perl? In Melbourne, Australia? We are hiring. -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
On Wed, Oct 28, 2009, Alan Tyree wrote: That's interesting, Daniel. So what are my tradeoffs. Run the normal kernel: faster but only 2.5gb; Run the bigmem kernel and suffer the performance but have more memory. Hm, does Linux actually -copy- data around when doing PAE? The whole point behind PAE is to give you a larger amount of address space usable by concurrent processes. So each process will have a differently mapped set of PAE RAM pages as needed, along with the shared kernel stuff. I know that FreeBSD will do some data copying to and from devices that are not PAE aware (ie, hardware that only addresses up to 4gig of memory space, and drivers which haven't been converted over) but for individual processes it isn't all that bad. Aside from the work mentioned above, I also edit some really big video files and do ffmpeg transformations on them. Right. In which case 64 bit is for you. So, is there some way of choosing which of the above is the best option for me? I'd suggest trying both out and see. Typically for things like graphics/video editing, I suggest 64 bit almost exclusively now because the programs are written assuming they can hold a lot of data in RAM. Adrian (Who isn't Daniel, but has hacked on a bit of PAE code in his time.) -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
Alan Tyree a...@austlii.edu.au writes: On Wed, Oct 28, 2009 at 12:51 PM, Daniel Pittman dan...@rimspace.netwrote: [...] It is there; the two common problems are that low memory fills, causing extra competition, and that your memory bandwidth is terribly reduced through extra TLB flushing to bounce data up above the easy line. You probably don't notice any performance hit because, frankly, almost every computer you can buy — including the one in your mobile phone — is sufficiently overpowered for the work it is asked to do[1] that you can sacrifice ten or twenty percent of performance[2] without noticing. That's interesting, Daniel. So what are my tradeoffs. Run the normal kernel: faster but only 2.5gb; Run the bigmem kernel and suffer the performance but have more memory. Pretty much. Alternately, use a 64-bit kernel, and this all goes away. (Use a 64-bit kernel and 32-bit userspace and it *still* goes away; according to some of the LKML developers this is their current approach and is pretty much trouble free — but that may have a ...if you are a kernel developer caveat attached to the pretty much part. ;) Aside from the work mentioned above, I also edit some really big video files and do ffmpeg transformations on them. So, is there some way of choosing which of the above is the best option for me? Yep: benchmark what you actually do. ;) Otherwise, no, there isn't any easy way to do it. Well, except that it is probably sensible to avoid the cost if you only have 1GB of RAM, total, in the machine. For an extra 1.5GB you /probably/ save enough just having it as disk cache that you have an overall win. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons Looking for work? Love Perl? In Melbourne, Australia? We are hiring. -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
Adrian Chadd adr...@creative.net.au writes: On Wed, Oct 28, 2009, Alan Tyree wrote: That's interesting, Daniel. So what are my tradeoffs. Run the normal kernel: faster but only 2.5gb; Run the bigmem kernel and suffer the performance but have more memory. Hm, does Linux actually -copy- data around when doing PAE? Sometimes, the same way as the FreeBSD stuff you mention, using bounce buffers to help incapable hardware out. The big performance hit is that 32-bit needs to keep page tables in low memory, which is a scarce resource, and that it needs to use the kmap / kunmap infrastructure to provide access to pages in high memory, outside the easily accessed address space. That later is where most of the cost comes from. The whole point behind PAE is to give you a larger amount of address space usable by concurrent processes. So each process will have a differently mapped set of PAE RAM pages as needed, along with the shared kernel stuff. Yeah. The real cost is the HIGHMEM stuff, not PAE directly, although that does increase pressure in low memory because the page tables are a bit bigger. Daniel -- ✣ Daniel Pittman✉ dan...@rimspace.net☎ +61 401 155 707 ♽ made with 100 percent post-consumer electrons Looking for work? Love Perl? In Melbourne, Australia? We are hiring. -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
[snip] Based on what you have said do yourself a favour and don't do LVM. LVM is a wonderful idea but it requires that you understand statistics related to disk failure and the consequences of that. This comment makes no sense to me: in what way does LVM change the risks associated with disk failure? I can't think of *anything* that is at all different in that regard. [snip] Heh. Aside from the LVM bit, this is almost certainly the best advice the OP has gotten. (Even LVM may be right; I just don't understand what James is trying to say the problem is yet. ;) From 2nd year stats (and subject to the ravages of time on my memory): a display array of 10x20 1000hour lamps will have a lamp fail on average every 20 min !! According to Seagate the failure rate of 2 disks is much greater than 2x failure rate of 1 disk http://portal.acm.org/citation.cfm?id=1090724 Along with all the cute benefits that LVM offer is a much higher disk failure rate. Is the windows-linux convert going to pay attention to needed backup regime? I don't believe it is in the best interest of this user to do kewl rad stuff! James -- 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] Advice Request for moving a Ubuntu installation to a larger disk and 4Gb RAM
jam wrote: Along with all the cute benefits that LVM offer is a much higher disk failure rate. Is the windows-linux convert going to pay attention to needed backup regime? And how exactly does LVM offer a much higher disk failure rate ? Cheers, -- Steve Why does everyone say 'Relax' when they're about to do something terrible? - Ensign Harry Kim, USS Voyager -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
