Re: [CentOS] When should LVM be used?
On Sat, Jul 31, 2010 at 8:52 AM, Drew drew@gmail.com wrote: LVM adds flexability that regular partitioning can't. Example 1. Say you've mounted an entire 2TB disk as /home and it's almost full. Now you want to add another 2TB to /home. How do you? Easiest way is with LVM. You just add the new disk into LVM's pool of storage and expand the home partition (Logical volume) to use the new space. Now you have a single filesystem spread across two disks. Example 2. Now let's say that you bought a NAS device (QNAP, Drobo, Buffalo) that does iSCSI or NFS and you want to move your data off the two local disks. With LVM you just add the new 'disk' into the pool then tell LVM to move existing data off the 'old' disk. Try doing that with parted. :-P I understand the advantages when using a server, but my personal computer is a Small Form Factor Dell GX270 with only one hard drive slot. But I'll look closer into LVM options when I install on the bigger hard drive. Thanks. -- RonB -- Using CentOS 5.5 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Mon, Aug 9, 2010 at 11:00 AM, Ron Blizzard rb4cen...@gmail.com wrote: On Sat, Jul 31, 2010 at 8:52 AM, Drew drew@gmail.com wrote: LVM adds flexability that regular partitioning can't. Example 1. Say you've mounted an entire 2TB disk as /home and it's almost full. Now you want to add another 2TB to /home. How do you? Easiest way is with LVM. You just add the new disk into LVM's pool of storage and expand the home partition (Logical volume) to use the new space. Now you have a single filesystem spread across two disks. Example 2. Now let's say that you bought a NAS device (QNAP, Drobo, Buffalo) that does iSCSI or NFS and you want to move your data off the two local disks. With LVM you just add the new 'disk' into the pool then tell LVM to move existing data off the 'old' disk. Try doing that with parted. :-P I understand the advantages when using a server, but my personal computer is a Small Form Factor Dell GX270 with only one hard drive slot. But I'll look closer into LVM options when I install on the bigger hard drive. Thanks. -- RonB -- Using CentOS 5.5 ___ Even in this case, LVM could be useful. In general, you don't want to put everything in on large partition. What do you do with 1TB's worth of data when you decide to upgrade CentOS 4 to 5 (as an example) or install Ubuntu? With LVM, you simply create a 900MB LVM volume for your data and reinstall the OS :) BUT, let's say you decide to allocate 10GB to /, 4GB to swap 1GB to /tmp. Suddenly your / partition is full and you can't install more stuff. With LVM you can quickly shrink /home and increase the size of /. All on the go without having to reboot. I found this very handy while working on a Windows VM installed on my home PC, which was busy doing some video rendering and I didn't want to stop the rendering to increse the / partition. -- Kind Regards Rudi Ahlers SoftDux Website: http://www.SoftDux.com Technical Blog: http://Blog.SoftDux.com Office: 087 805 9573 Cell: 082 554 7532 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
BUT, let's say you decide to allocate 10GB to /, 4GB to swap 1GB to /tmp. Suddenly your / partition is full and you can't install more stuff. With LVM you can quickly shrink /home and increase the size of /. All on the go without having to reboot. I found this very handy while working on a Windows VM installed on my home PC, which was busy doing some video rendering and I didn't want to stop the rendering to increse the / partition. Just a note to say this behaviour is dependant on the filesystem on top of the LVM logical volume Some (most?) will require you to take the mounted volume offline to shrink with not all allowing online increasing of size... so it is important to double check the documentation for your filesystem before carrying out such an exercise whilst the volume is mounted... and of course as with any changes to partitioning information and volumes ensure you have a backup of the data when resizing (especially shrinking) in case of any corruption or issues in the process James ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
At Mon, 9 Aug 2010 04:00:27 -0500 CentOS mailing list centos@centos.org wrote: On Sat, Jul 31, 2010 at 8:52 AM, Drew drew@gmail.com wrote: LVM adds flexability that regular partitioning can't. Example 1. Say you've mounted an entire 2TB disk as /home and it's almost full. Now you want to add another 2TB to /home. How do you? Easiest way is with LVM. You just add the new disk into LVM's pool of storage and expand the home partition (Logical volume) to use the new space. Now you have a single filesystem spread across two disks. Example 2. Now let's say that you bought a NAS device (QNAP, Drobo, Buffalo) that does iSCSI or NFS and you want to move your data off the two local disks. With LVM you just add the new 'disk' into the pool then tell LVM to move existing data off the 'old' disk. Try doing that with parted. :-P I understand the advantages when using a server, but my personal computer is a Small Form Factor Dell GX270 with only one hard drive slot. But I'll look closer into LVM options when I install on the bigger hard drive. Thanks. I use LVM on my *laptop* with a 40 gig hard drive... Very convientent, esp. when I upgraded from CentOS 4.8 to CentOS 5.mumble. My laptop does NOT have any removable media -- that is it is NOT possible to boot off a live CD to repartition the hard drive, so using something like parted is not really a useful option. I can do a PXE boot and run the installer that way. Is is just easier to be able to 'repartition' while running the live system (eg doing lvcreate, lvresize, etc. as needed). -- Robert Heller -- Get the Deepwoods Software FireFox Toolbar! Deepwoods Software-- Linux Installation and Administration http://www.deepsoft.com/ -- Web Hosting, with CGI and Database hel...@deepsoft.com -- Contract Programming: C/C++, Tcl/Tk ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
I understand the advantages when using a server, but my personal computer is a Small Form Factor Dell GX270 with only one hard drive slot. But I'll look closer into LVM options when I install on the bigger hard drive. Thanks. Those examples actually came from situations I faced with a home PC. :) I had a small VIA Epia based PC with a 40GB internal drive that I had to expand because it didn't have enough space. I added a couple of external USB enclosures and expanded that way. Later on I ended up migrating the same data off the external enclosures and onto a QNAP I'd acquired because the USB enclosures were too small. -- Drew Nothing in life is to be feared. It is only to be understood. --Marie Curie ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On 31 July 2010 14:52, Drew drew@gmail.com wrote: Is there any reason to use LVM on a personal desktop install of CentOS? It seems to me, for my purposes, that LVM is just a pain in the neck -- although I've always just let CentOS set it up during the install in the past. I would like to be able to use parted to resize partitions when I want to, and also I'd like Vector Linux to be able to read and write data to the CentOS partition. Would I be missing something by not installing LVM, or is this mostly for server purposes anyhow? LVM adds flexability that regular partitioning can't. Just to add some more info to the conversation. Yesterday i found out that if you have a modern SSD and are planning on using RHEL6 or CentOS6 then LVM will not support the TRIM ATA command thus there will be a significant decrease in the write perfomnace of the drive with time. Linux swap will use it but the only way to enable this feature is if your partitions are native ext4 and you use the discard option. Thus TRIM will not be enabled by a default install except for swap space. mike ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
Ron Blizzard wrote, On 07/30/2010 05:16 PM: On Fri, Jul 30, 2010 at 8:33 AM, Todd Denniston todd.dennis...@tsb.cranrdte.navy.mil wrote: Best use for LVM I have seen... Reducing the number of times you need to enter the LUKS pass phrase to once per boot, i.e., one LUKS containing an LVM of / and Swap so that the system can boot with one entry of the pass phrase and if you then have other partitions, such as an independent /home, /etc/crypttab can be used (with appropriately constructed and protected cryptpassphrase files). At this point I don't even know what a LUKS pass phrase is -- is this something I'm liable to run into on a home desktop computer? Depends on how much you value not letting other folks at your data, with out your permission after you have properly powered down the machine. :) LUKS is used with encrypted partitions/filesystems. I have only used it at the partition level. It is most easily setup at install time, because anaconda gets the incantations correct for you. Suggested further reading: http://wiki.centos.org/HowTos/EncryptedFilesystem http://wiki.centos.org/TipsAndTricks/EncryptedFilesystem/Scripts http://en.wikipedia.org/wiki/Linux_Unified_Key_Setup -- Todd Denniston Crane Division, Naval Surface Warfare Center (NSWC Crane) Harnessing the Power of Technology for the Warfighter ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Sun, Aug 1, 2010 at 6:35 AM, JohnS jse...@gmail.com wrote: On Sat, 2010-07-31 at 05:32 -0700, Drew wrote: I'd still want a separate partition for /var for the SAN configuration. I've seen more then one machine brought to it's knees by overflowing log entries. --- I can't really argue that point there. I've seen iptables do the same as also auditd. Carefulness in log watching is the key. You check your logs? John I do. Daily emails with copies of all logs and a summary disk usage statement of all partitions. I learned my lesson about log files a while back. ;-) -- Drew Nothing in life is to be feared. It is only to be understood. --Marie Curie ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Sat, 2010-07-31 at 05:32 -0700, Drew wrote: Yea the default works but how is it Plain Wrong? If it was flat out wrong then Upstream would not allow it. Raid 1 disk array with one hot spare on a hardware raid controller under a SAN server is what you saying is wrong? Case is, the array is not using /home or /var; were only exporting nfs luns direct attached. What on earth and why would I want to have another drive for /var /home in this case. I'm just asking but not arguing. There are cases where it works exceptionally. In fact my opinion is it works nice for newbies, untill they gets a lil experience. I'd still want a separate partition for /var for the SAN configuration. I've seen more then one machine brought to it's knees by overflowing log entries. --- I can't really argue that point there. I've seen iptables do the same as also auditd. Carefulness in log watching is the key. You check your logs? John ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
Yea the default works but how is it Plain Wrong? If it was flat out wrong then Upstream would not allow it. Raid 1 disk array with one hot spare on a hardware raid controller under a SAN server is what you saying is wrong? Case is, the array is not using /home or /var; were only exporting nfs luns direct attached. What on earth and why would I want to have another drive for /var /home in this case. I'm just asking but not arguing. There are cases where it works exceptionally. In fact my opinion is it works nice for newbies, untill they gets a lil experience. I'd still want a separate partition for /var for the SAN configuration. I've seen more then one machine brought to it's knees by overflowing log entries. -- Drew Nothing in life is to be feared. It is only to be understood. --Marie Curie ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
Is there any reason to use LVM on a personal desktop install of CentOS? It seems to me, for my purposes, that LVM is just a pain in the neck -- although I've always just let CentOS set it up during the install in the past. I would like to be able to use parted to resize partitions when I want to, and also I'd like Vector Linux to be able to read and write data to the CentOS partition. Would I be missing something by not installing LVM, or is this mostly for server purposes anyhow? LVM adds flexability that regular partitioning can't. Example 1. Say you've mounted an entire 2TB disk as /home and it's almost full. Now you want to add another 2TB to /home. How do you? Easiest way is with LVM. You just add the new disk into LVM's pool of storage and expand the home partition (Logical volume) to use the new space. Now you have a single filesystem spread across two disks. Example 2. Now let's say that you bought a NAS device (QNAP, Drobo, Buffalo) that does iSCSI or NFS and you want to move your data off the two local disks. With LVM you just add the new 'disk' into the pool then tell LVM to move existing data off the 'old' disk. Try doing that with parted. :-P -- Drew Nothing in life is to be feared. It is only to be understood. --Marie Curie ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On 07/30/2010 07:37 AM, Ron Blizzard wrote: In my old computer I have a much bigger hard drive then in this one -- and I plan to hand that old computer down to one of my sons -- keeping his current drive from an even older computer. Currently the hard drive on my old computer has SuSE Linux, but that will go. I'll rebuild CentOS 5.5 on it, but I want to leave some free space for whatever comes up and also dual-boot Vector Linux. Which, at last, brings me to the question... Is there any reason to use LVM on a personal desktop install of CentOS? It seems to me, for my purposes, that LVM is just a pain in the neck -- although I've always just let CentOS set it up during the install in the past. I would like to be able to use parted to resize partitions when I want to, and also I'd like Vector Linux to be able to read and write data to the CentOS partition. Would I be missing something by not installing LVM, or is this mostly for server purposes anyhow? Thanks for any pointers. * snaphotting (great for db backup) * resizing partition * online partitioning ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
At Fri, 30 Jul 2010 00:37:21 -0500 CentOS mailing list centos@centos.org wrote: In my old computer I have a much bigger hard drive then in this one -- and I plan to hand that old computer down to one of my sons -- keeping his current drive from an even older computer. Currently the hard drive on my old computer has SuSE Linux, but that will go. I'll rebuild CentOS 5.5 on it, but I want to leave some free space for whatever comes up and also dual-boot Vector Linux. Which, at last, brings me to the question... Is there any reason to use LVM on a personal desktop install of CentOS? It seems to me, for my purposes, that LVM is just a pain in the neck -- although I've always just let CentOS set it up during the install in the past. I would like to be able to use parted to resize partitions when I want to, and also I'd like Vector Linux to be able to read and write data to the CentOS partition. Would I be missing something by not installing LVM, or is this mostly for server purposes anyhow? LVM has a number of useful features and advantages. The 'default' RedHat/CentOS LVM setup (basically creating one LVM volume taking up all available space for the root file system), is pretty useless. With modern *large* disks. LVM (if set up properly) allows creating and/or resizing logical disks without having to shutdown and/or rebooting the system. This is often usefull for installing virtual processes (eg with xen). Thanks for any pointers. -- Robert Heller -- Get the Deepwoods Software FireFox Toolbar! Deepwoods Software-- Linux Installation and Administration http://www.deepsoft.com/ -- Web Hosting, with CGI and Database hel...@deepsoft.com -- Contract Programming: C/C++, Tcl/Tk ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On 07/29/2010 10:57 PM, Fajar Priyanto wrote: On Fri, Jul 30, 2010 at 1:37 PM, Ron Blizzardrb4cen...@gmail.com wrote: Is there any reason to use LVM on a personal desktop install of CentOS? It seems to me, for my purposes, that LVM is just a pain in the neck -- although I've always just let CentOS set it up during the install in the past. I would like to be able to use parted to resize partitions when I want to, and also I'd like Vector Linux to be able to read and write data to the CentOS partition. Would I be missing something by not installing LVM, or is this mostly for server purposes anyhow? You don't need LVM if you don't plan to expand the filesystem (or a particular mount point). You can use LVM for taking snapshots as well (very useful if you want to quiesce databases for the shortest possible time for backups) . And you can use LVM to migrate data from an old drive to a new one or even to *shrink* a partition. I've never found LVM to 'be a pain'. 99% of the time it's invisible, and 1% of the time it's indispensable. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
Ron Blizzard wrote, On 07/30/2010 01:37 AM: Is there any reason to use LVM on a personal desktop install of CentOS? It seems to me, for my purposes, that LVM is just a pain in the neck -- although I've always just let CentOS set it up during the install in the past. I would like to be able to use parted to resize partitions when I want to, and also I'd like Vector Linux to be able to read and write data to the CentOS partition. Would I be missing something by not installing LVM, or is this mostly for server purposes anyhow? Thanks for any pointers. Best use for LVM I have seen... Reducing the number of times you need to enter the LUKS pass phrase to once per boot, i.e., one LUKS containing an LVM of / and Swap so that the system can boot with one entry of the pass phrase and if you then have other partitions, such as an independent /home, /etc/crypttab can be used (with appropriately constructed and protected cryptpassphrase files). -- Todd Denniston Crane Division, Naval Surface Warfare Center (NSWC Crane) Harnessing the Power of Technology for the Warfighter ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Fri, Jul 30, 2010 at 12:57 AM, Fajar Priyanto fajar...@arinet.org wrote: You don't need LVM if you don't plan to expand the filesystem (or a particular mount point). Okay, thanks. By reading the responses, it appears the very least I should do is not let CentOS do a standard setup -- in other words I should save some space on the hard drive. -- RonB -- Using CentOS 5.5 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Fri, Jul 30, 2010 at 5:50 AM, Juergen Gotteswinter j...@internetx.de wrote: * snaphotting (great for db backup) * resizing partition * online partitioning I didn't know LVM would do snapshots -- I'll have to look into that. But I'm guessing the feature is pretty much worthless if the whole hard drive is taken up by one LVM partition -- which has been my CentOS default setups. Thanks. -- RonB -- Using CentOS 5.5 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Fri, Jul 30, 2010 at 6:18 AM, Robert Heller hel...@deepsoft.com wrote: LVM has a number of useful features and advantages. The 'default' RedHat/CentOS LVM setup (basically creating one LVM volume taking up all available space for the root file system), is pretty useless. With modern *large* disks. LVM (if set up properly) allows creating and/or resizing logical disks without having to shutdown and/or rebooting the system. This is often usefull for installing virtual processes (eg with xen). Thanks. I don't know if my 160 Gig hard drive would qualify as a modern *large* disk or not, but it's definitely bigger than the current 20 Gig one. I thought an external USB drive would work fine, but I'm finding the current situation is too cramped. Is there any way to mount an LVM partition from another Linux distribution? -- RonB -- Using CentOS 5.5 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Fri, Jul 30, 2010 at 8:13 AM, Benjamin Franz jfr...@freerun.com wrote: You can use LVM for taking snapshots as well (very useful if you want to quiesce databases for the shortest possible time for backups) . And you can use LVM to migrate data from an old drive to a new one or even to *shrink* a partition. I've never found LVM to 'be a pain'. 99% of the time it's invisible, and 1% of the time it's indispensable. I guess my ignorance is showing. It could also be that the small hard drives that I usually use with CentOS really can't take advantage of this feature. So far I haven't done much with servers, but I have been experimenting with Asterisk and plan to work through the Foundations of CentOS -- so that should change. -- RonB -- Using CentOS 5.5 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Fri, Jul 30, 2010 at 8:33 AM, Todd Denniston todd.dennis...@tsb.cranrdte.navy.mil wrote: Best use for LVM I have seen... Reducing the number of times you need to enter the LUKS pass phrase to once per boot, i.e., one LUKS containing an LVM of / and Swap so that the system can boot with one entry of the pass phrase and if you then have other partitions, such as an independent /home, /etc/crypttab can be used (with appropriately constructed and protected cryptpassphrase files). At this point I don't even know what a LUKS pass phrase is -- is this something I'm liable to run into on a home desktop computer? -- RonB -- Using CentOS 5.5 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Fri, Jul 30, 2010 at 04:11:17PM -0500, Ron Blizzard wrote: Is there any way to mount an LVM partition from another Linux distribution? Yes. They all support it. You might have to install a package for it, but it's been standard for a few years pretty much across the board. Whit ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
At Fri, 30 Jul 2010 16:07:39 -0500 CentOS mailing list centos@centos.org wrote: On Fri, Jul 30, 2010 at 5:50 AM, Juergen Gotteswinter j...@internetx.de wrote: * snaphotting (great for db backup) * resizing partition * online partitioning I didn't know LVM would do snapshots -- I'll have to look into that. But I'm guessing the feature is pretty much worthless if the whole hard drive is taken up by one LVM partition -- which has been my CentOS default setups. Yes, the *default* setup is just plain wrong, and in general should NOT be used. Yes, the default works (one big happy filesystem), and actually might make sense for a virtual server, but otherwise no. See http://www.deepsoft.com/2006/03/partitioning-for-linux/ for some thoughts on partitioning for Linux (also applies to LVM volumes). Thanks. -- Robert Heller -- Get the Deepwoods Software FireFox Toolbar! Deepwoods Software-- Linux Installation and Administration http://www.deepsoft.com/ -- Web Hosting, with CGI and Database hel...@deepsoft.com -- Contract Programming: C/C++, Tcl/Tk ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Fri, 2010-07-30 at 17:32 -0400, Robert Heller wrote: Yes, the *default* setup is just plain wrong, and in general should NOT be used. Yes, the default works (one big happy filesystem), and actually might make sense for a virtual server, but otherwise no. See Yea the default works but how is it Plain Wrong? If it was flat out wrong then Upstream would not allow it. Raid 1 disk array with one hot spare on a hardware raid controller under a SAN server is what you saying is wrong? Case is, the array is not using /home or /var; were only exporting nfs luns direct attached. What on earth and why would I want to have another drive for /var /home in this case. I'm just asking but not arguing. There are cases where it works exceptionally. In fact my opinion is it works nice for newbies, untill they gets a lil experience. http://www.deepsoft.com/2006/03/partitioning-for-linux/ With number one I do not agree. You can install apps under winblows in any location. Not every Unix/Linux system has the same file layout. Debian vs CentOS John ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] When should LVM be used?
On Fri, Jul 30, 2010 at 1:37 PM, Ron Blizzard rb4cen...@gmail.com wrote: Is there any reason to use LVM on a personal desktop install of CentOS? It seems to me, for my purposes, that LVM is just a pain in the neck -- although I've always just let CentOS set it up during the install in the past. I would like to be able to use parted to resize partitions when I want to, and also I'd like Vector Linux to be able to read and write data to the CentOS partition. Would I be missing something by not installing LVM, or is this mostly for server purposes anyhow? You don't need LVM if you don't plan to expand the filesystem (or a particular mount point). ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
