I’ve got an lvm volume group that I want to changing from using raid0, to using raid1.
The volume group is made up for a few raid0 volumes. To change the storage, I do the following:
pvmove the data off at least one of the physical volumes.
[root@wizards nelg]# pvs PV VG Fmt Attr PSize PFree /dev/md1 system lvm2 a- 44.92G 8.32G /dev/md2 system lvm2 a- 46.87G 19.87G /dev/md3 other lvm2 -- 93.75G 93.75G /dev/md4 other lvm2 -- 93.75G 93.75G /dev/md5 other lvm2 a- 93.75G 1.73G /dev/md6 other lvm2 a- 92.62G 0 /dev/md7 data lvm2 a- 306.41G 52.67G /dev/md8 data lvm2 a- 306.41G 62.67G /dev/md9 data lvm2 a- 318.68G 133.21G [root@wizards nelg]#
vgreduce the volume,
then remove it:
lvm> vgreduce other /dev/md3 Removed "/dev/md3" from volume group "other" lvm> pvremove /dev/md3 Labels on physical volume "/dev/md3" successfully wiped lvm> pvs PV VG Fmt Attr PSize PFree /dev/md1 system lvm2 a- 44.92G 8.32G /dev/md2 system lvm2 a- 46.87G 19.87G /dev/md3 lvm2 -- 93.75G 93.75G /dev/md4 other lvm2 -- 93.75G 93.75G /dev/md5 other lvm2 a- 93.75G 1.73G /dev/md6 other lvm2 a- 92.62G 0 /dev/md7 data lvm2 a- 306.41G 52.67G /dev/md8 data lvm2 a- 306.41G 62.67G /dev/md9 data lvm2 a- 318.68G 133.21G lvm>
The device looks like this currently in mdadm
mdadm -D /dev/md3
/dev/md3:
Version : 00.90.03
Creation Time : Sun Jan 8 23:02:59 2006
Raid Level : raid0
Array Size : 98301440 (93.75 GiB 100.66 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 3
Persistence : Superblock is persistent
Update Time : Mon Jul 7 20:46:54 2008
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Chunk Size : 64K
UUID : 2b3493e2:0a59d252:d9ed1514:2cb69c87
Events : 0.3
Number Major Minor RaidDevice State
0 3 7 0 active sync /dev/hda7
1 3 71 1 active sync /dev/hdb7
Stop the device
[root@wizards nelg]# mdadm -S /dev/md3 mdadm: stopped /dev/md3
This means the pvs shows:
[root@wizards nelg]# pvs PV VG Fmt Attr PSize PFree /dev/md1 system lvm2 a- 44.92G 8.32G /dev/md2 system lvm2 a- 46.87G 19.87G /dev/md4 other lvm2 -- 93.75G 93.75G /dev/md5 other lvm2 a- 93.75G 1.73G /dev/md6 other lvm2 a- 92.62G 0 /dev/md7 data lvm2 a- 306.41G 52.67G /dev/md8 data lvm2 a- 306.41G 62.67G /dev/md9 data lvm2 a- 318.68G 133.21G
Now, all that is remaining is to change the device, update /dev/mdadm.conf and rebuild initrd to reflect the change.
So. Double check that devices are not in a current array:
grep hda7 /proc/mdstat
grep hdb7 /proc/mdstat
Build the new device
mdadm --create /dev/md3 -l 1 -n 2 /dev/hda7 /dev/hdb7
This will warn, as per below
[root@wizards nelg]# mdadm --create /dev/md3 -l 1 -n 2 /dev/hda7 /dev/hdb7
mdadm: /dev/hda7 appears to be part of a raid array:
level=raid0 devices=2 ctime=Sun Jan 8 23:02:59 2006
mdadm: /dev/hdb7 appears to be part of a raid array:
level=raid0 devices=2 ctime=Sun Jan 8 23:02:59 2006
Continue creating array? y
mdadm: array /dev/md3 started.
This now has a new device, as per below.
[root@wizards nelg]# mdadm -D /dev/md3
/dev/md3:
Version : 00.90.03
Creation Time : Tue Jul 22 20:49:22 2008
Raid Level : raid1
Array Size : 49150720 (46.87 GiB 50.33 GB)
Used Dev Size : 49150720 (46.87 GiB 50.33 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 3
Persistence : Superblock is persistent
Update Time : Tue Jul 22 20:49:22 2008
State : clean, resyncing
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Rebuild Status : 3% complete
UUID : 60f87451:d385361e:c4cdb003:fcc220ea
Events : 0.1
Number Major Minor RaidDevice State
0 3 7 0 active sync /dev/hda7
1 3 71 1 active sync /dev/hdb7
[root@wizards nelg]#
Notice that the devices are being synced.
/proc/mdstat shows:
md3 : active raid1 hdb7[1] hda7[0]
49150720 blocks [2/2] [UU]
[==>..................] resync = 13.3% (6540864/49150720) finish=23.3min speed=30358K/sec
Now, I take the UUID: 60f87451:d385361e:c4cdb003:fcc220ea and update /etc/mdadm.conf to reflect this.
I.e.
-ARRAY /dev/md3 UUID=2b3493e2:0a59d252:d9ed1514:2cb69c87 auto=yes +ARRAY /dev/md3 UUID=60f87451:d385361e:c4cdb003:fcc220ea auto=yes
Next is to update initrd.
The is two choices. Build a new initrd, or just change this one.
As I like to be able to boot my system, I’ll do both, so I have a spare if one does not work.
Approach 1
[root@wizards boot]# mkdir tt2 [root@wizards boot]# cd tt2 [root@wizards tt2]# cat ../initrd-2.6.24.5-server-2mnb.img | gzip -d -c | cpio -i 12546 blocks [root@wizards tt2] ls etc blkid/ ld.so.cache ld.so.conf ld.so.conf.d/ lvm/ mdadm.conf suspend.conf [root@wizards tt2]# pwd /boot/tt2
So, as you can see, the is an mdadm.conf in the initrd file.
cp /etc/mdadm.conf /boot/tt2/etc/
the, put the initrd back together.
find . | cpio -H newc --quiet -o | gzip -9 > ../initrd-2.6.24.5-server-2mnb-new.img
Note, I made this a new name, as I don’t like to overwrite my existing initrd, just in case. So, I’ll just change my symlink to use this one.
Approach 2
mkinitrd /boot/initrd-2.6.24.5-server-2mnb-new1.img $(uname -r)
Both approaches should work. I’ll comment further if one does not.
Now, last but not least, is to make use of our new device.
In my case, create a new volume group for my virtual machines, after adding this device to lvm.
lvm> pvcreate /dev/md3 Physical volume "/dev/md3" successfully created lvm> vgcreate virtualmachines /dev/md3 Volume group "virtualmachines" successfully created lvm> vgs VG #PV #LV #SN Attr VSize VFree data 3 3 0 wz--n- 931.51G 248.54G other 3 1 0 wz--n- 280.12G 95.48G system 2 6 0 wz--n- 91.79G 28.19G virtualmachines 1 0 0 wz--n- 46.87G 46.87G lvm> lvcreate -n ms -L 5G virtualmachines Logical volume "ms" created lvm> lvdisplay /dev/mapper/virtualmachines-ms --- Logical volume --- LV Name /dev/virtualmachines/ms VG Name virtualmachines LV UUID GGV1PY-mi9Q-yqBz-3bFE-U3Fa-bpS9-pou7fX LV Write Access read/write LV Status available # open 0 LV Size 5.00 GB Current LE 1280 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 252:10 lvm>
now, just format it.
[root@wizards boot]# mkfs.xfs /dev/virtualmachines/ms
meta-data=/dev/virtualmachines/ms isize=256 agcount=4, agsize=327680 blks
= sectsz=512 attr=2
data = bsize=4096 blocks=1310720, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
[root@wizards boot]#
and mount
[root@wizards /]# df -h /virtualmachines/ms/
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/virtualmachines-ms
5.0G 4.2M 5.0G 1% /virtualmachines/ms
[root@wizards /]#
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