Re: [CentOS] Questions about software RAID, LVM.
On Thu, Feb 14, 2013 at 11:58 PM, Ted Miller tedli...@sbcglobal.net wrote: On 02/04/2013 06:40 PM, Robert Heller wrote: I am planning to increase the disk space on my desktop system. It is running CentOS 5.9 w/XEN. I have two 160Gig 2.5 laptop (2.5) SATA drives in two slots of a 4-slot hot swap bay configured like this: Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 125 1004031 fd Linux raid autodetect /dev/sda2 126 19457 155284290 fd Linux raid autodetect Disk /dev/sdb: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 1 125 1004031 fd Linux raid autodetect /dev/sdb2 126 19457 155284290 fd Linux raid autodetect sauron.deepsoft.com% cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb1[1] sda1[0] 1003904 blocks [2/2] [UU] md1 : active raid1 sdb2[1] sda2[0] 155284224 blocks [2/2] [UU] unused devices:none That is I have two RAID1 arrays: a small (1Gig) one mounted as /boot and a larger 148Gig one that is a LVM Volume Group (which contains a pile of file systems, some for DOM0 and some that are for other VMs). What I plan on doing is getting a pair of 320Gig 2.5 (laptop) SATA disks and fail over the existing disks to this new pair. I believe I can then 'grow' the second RAID array to be like ~300Gig. My question is: what happens to the LVM Volume Group? Will it grow when the RAID array grows? Not on its own, but you can grow it. I believe the recommended way to do the LVM volume is to partition new drive as type fd LVM is 8e Software RAID is fd install new PV on new partition (will be new, larger size) make new PV part of old volume group migrate all volumes on old PV onto new PV remove old PV from volume group You have to do this separately for each drive, but it isn't very hard. Of course your boot partition will have to be handled separately. This is what I said ;) http://lists.centos.org/pipermail/centos/2013-February/131917.html Or should I leave /dev/md1 its current size and create a new RAID array and add this as a second PV and grow the Volume Group that way? That is a solution to a different problem. You would end up with a VG of about 450 GB total. If that is what you want to do, that works too. He has to leave /dev/md1 at its current size ... it's a raid1. The documentation is not clear as to what happens -- the VG is marked 'resisable'. sauron.deepsoft.com% sudo pvdisplay --- Physical volume --- PV Name /dev/md1 VG Name sauron PV Size 148.09 GB / not usable 768.00 KB Allocatable yes PE Size (KByte) 4096 Total PE 37911 Free PE 204 Allocated PE 37707 PV UUID ttB15B-3eWx-4ioj-TUvm-lAPM-z9rD-Prumee sauron.deepsoft.com% sudo vgdisplay --- Volume group --- VG Name sauron System ID Formatlvm2 Metadata Areas1 Metadata Sequence No 65 VG Access read/write VG Status resizable MAX LV0 Cur LV17 Open LV 12 Max PV0 Cur PV1 Act PV1 VG Size 148.09 GB PE Size 4.00 MB Total PE 37911 Alloc PE / Size 37707 / 147.29 GB Free PE / Size 204 / 816.00 MB VG UUID qG8gCf-3vou-7dp2-Ar0B-p8jz-eXZF-3vOONr Doesn't look like anyone answered your question, so I'll tell you that the answer is Yes. Ted Miller ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos -- ---~~.~~--- Mike // SilverTip257 // ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Questions about software RAID, LVM.
On 02/04/2013 06:40 PM, Robert Heller wrote: I am planning to increase the disk space on my desktop system. It is running CentOS 5.9 w/XEN. I have two 160Gig 2.5 laptop (2.5) SATA drives in two slots of a 4-slot hot swap bay configured like this: Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 125 1004031 fd Linux raid autodetect /dev/sda2 126 19457 155284290 fd Linux raid autodetect Disk /dev/sdb: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sdb1 * 1 125 1004031 fd Linux raid autodetect /dev/sdb2 126 19457 155284290 fd Linux raid autodetect sauron.deepsoft.com% cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb1[1] sda1[0] 1003904 blocks [2/2] [UU] md1 : active raid1 sdb2[1] sda2[0] 155284224 blocks [2/2] [UU] unused devices:none That is I have two RAID1 arrays: a small (1Gig) one mounted as /boot and a larger 148Gig one that is a LVM Volume Group (which contains a pile of file systems, some for DOM0 and some that are for other VMs). What I plan on doing is getting a pair of 320Gig 2.5 (laptop) SATA disks and fail over the existing disks to this new pair. I believe I can then 'grow' the second RAID array to be like ~300Gig. My question is: what happens to the LVM Volume Group? Will it grow when the RAID array grows? Not on its own, but you can grow it. I believe the recommended way to do the LVM volume is to partition new drive as type fd install new PV on new partition (will be new, larger size) make new PV part of old volume group migrate all volumes on old PV onto new PV remove old PV from volume group You have to do this separately for each drive, but it isn't very hard. Of course your boot partition will have to be handled separately. Or should I leave /dev/md1 its current size and create a new RAID array and add this as a second PV and grow the Volume Group that way? That is a solution to a different problem. You would end up with a VG of about 450 GB total. If that is what you want to do, that works too. The documentation is not clear as to what happens -- the VG is marked 'resisable'. sauron.deepsoft.com% sudo pvdisplay --- Physical volume --- PV Name /dev/md1 VG Name sauron PV Size 148.09 GB / not usable 768.00 KB Allocatable yes PE Size (KByte) 4096 Total PE 37911 Free PE 204 Allocated PE 37707 PV UUID ttB15B-3eWx-4ioj-TUvm-lAPM-z9rD-Prumee sauron.deepsoft.com% sudo vgdisplay --- Volume group --- VG Name sauron System ID Formatlvm2 Metadata Areas1 Metadata Sequence No 65 VG Access read/write VG Status resizable MAX LV0 Cur LV17 Open LV 12 Max PV0 Cur PV1 Act PV1 VG Size 148.09 GB PE Size 4.00 MB Total PE 37911 Alloc PE / Size 37707 / 147.29 GB Free PE / Size 204 / 816.00 MB VG UUID qG8gCf-3vou-7dp2-Ar0B-p8jz-eXZF-3vOONr Doesn't look like anyone answered your question, so I'll tell you that the answer is Yes. Ted Miller ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Questions about software RAID, LVM.
On Mon, Feb 4, 2013 at 6:40 PM, Robert Heller hel...@deepsoft.com wrote: I am planning to increase the disk space on my desktop system. It is running CentOS 5.9 w/XEN. I have two 160Gig 2.5 laptop (2.5) SATA drives in two slots of a 4-slot hot swap bay configured like this: I would certainly suggest testing these steps out in some form or another as a dry run. And verify your backups and/or create new ones ahead of time. :) Create your new softraid mirror with the larger disks, add that device (we'll say md3 - since the new /boot will be md2 temporarily) to your existing LVM volume group, then pvmove the physical extents from the existing disk /dev/md1 to /dev/md3. Then verify that the extents have been moved off md1 and are on md3. Finally remove md1 from the VG with pvremove. I don't recall if I specifically used these notes, but the process matches the one I used. [0] A few more bits of info I recognize from my readings a while back. [1] [2] [3] I expect you could easily tweak your mdadm config and rebuild your initial ramdisk so that the next time you reboot there isn't an issue. This all depends on how much of this process you plan on doing online. [0] http://www.rhcedan.com/2010/10/20/migrating-physical-volumes-in-a-lvm2-volume-group/ [1] http://www.centos.org/docs/5/html/Cluster_Logical_Volume_Manager/move_new_ex4.html [2] http://tldp.org/HOWTO/LVM-HOWTO/removeadisk.html [3] http://www.whmcr.com/2011/06/21/moving-part-of-an-lvm-vg-from-one-pv-to-another/ sauron.deepsoft.com% cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb1[1] sda1[0] 1003904 blocks [2/2] [UU] md1 : active raid1 sdb2[1] sda2[0] 155284224 blocks [2/2] [UU] unused devices: none That is I have two RAID1 arrays: a small (1Gig) one mounted as /boot and a larger 148Gig one that is a LVM Volume Group (which contains a pile of file systems, some for DOM0 and some that are for other VMs). What I plan on doing is getting a pair of 320Gig 2.5 (laptop) SATA disks and fail over the existing disks to this new pair. I believe I can then 'grow' the second RAID array to be like ~300Gig. My question is: what happens to the LVM Volume Group? Will it grow when the RAID In my experience the VG will grow by whatever extents the new PV has. I found it quite helpful to use loopback devices to test possible softraid and/or LVM scenarios. array grows? Or should I leave /dev/md1 its current size and create a new RAID array and add this as a second PV and grow the Volume Group Just add md3 to the VG and move the extents as noted above. that way? The documentation is not clear as to what happens -- the VG is marked 'resisable'. The biggest gotcha is with PVs. Example even though this doesn't apply: In that if you plan on enlarging a disk (ex: LVM backing for a VM that uses LVM), the PV in the VM has to be offline to resize (the OS doesn't recognize the larger disk until after a reboot, but cannot be resized since the PV is online again!). You avoid that pitfall since you will have a separate disk (md3) that can be hot added. sauron.deepsoft.com% sudo pvdisplay --- Physical volume --- PV Name /dev/md1 VG Name sauron PV Size 148.09 GB / not usable 768.00 KB Allocatable yes PE Size (KByte) 4096 Total PE 37911 Free PE 204 Allocated PE 37707 PV UUID ttB15B-3eWx-4ioj-TUvm-lAPM-z9rD-Prumee sauron.deepsoft.com% sudo vgdisplay --- Volume group --- VG Name sauron System ID Formatlvm2 Metadata Areas1 Metadata Sequence No 65 VG Access read/write VG Status resizable MAX LV0 Cur LV17 Open LV 12 Max PV0 Cur PV1 Act PV1 VG Size 148.09 GB PE Size 4.00 MB Total PE 37911 Alloc PE / Size 37707 / 147.29 GB Free PE / Size 204 / 816.00 MB VG UUID qG8gCf-3vou-7dp2-Ar0B-p8jz-eXZF-3vOONr -- Robert Heller -- 978-544-6933 / hel...@deepsoft.com Deepwoods Software-- http://www.deepsoft.com/ () ascii ribbon campaign -- against html e-mail /\ www.asciiribbon.org -- against proprietary attachments ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos Hope this helps. Best Regards, -- ---~~.~~--- Mike // SilverTip257 // ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
