hosed raid 1 under lvm
calling all lvm/raid gurus....
I'm running debian sarge and I have/had a 200GB raid 1 devices with LVM2
on top. The raid one was made from hdb1 and hdc1. Recently when I was
trying to change the size of a logical volume. I noticed that my vg was
using /dev/hdc1 as a physical volume instead of /dev/md0.
$ pvscan
Found duplicate PV YDMoRSv4EKZXHNPuchid5hPIwmXDCBCm: using
/dev/hdb1 not /dev/hdc1
PV /dev/hda4 VG LVM lvm2 [68.96 GB / 0 free]
PV /dev/hdc1 VG data lvm2 [186.30 GB / 4.00 MB free]
Total: 2 [255.26 GB] / in use: 2 [255.26 GB] / in no VG: 0 [0 ]
some additional digging and I found that my raid devices is inactive
$ mdadm -D /dev/md0
mdadm: md device /dev/md0 does not appear to be active.
but the mdsuperblock still seems present on both devices
$mdadm -E /dev/hdb1
/dev/hdb1:
Magic : a92b4efc
Version : 00.90.00
UUID : 9dc1df9b:771959ca:53ed751d:7b3b40ba
Creation Time : Sun Apr 17 13:24:05 2005
Raid Level : raid1
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
Update Time : Fri May 13 16:52:37 2005
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Checksum : 1dcab098 - correct
Events : 0.482221
Number Major Minor RaidDevice State
this 1 3 65 1 active sync
/dev/.static/dev/hdb1
0 0 22 1 0 active sync
/dev/.static/dev/hdc1
1 1 3 65 1 active sync
/dev/.static/dev/hdb1
$ mdadm /dev/hdc1
/dev/hdc1:
Magic : a92b4efc
Version : 00.90.00
UUID : 9dc1df9b:771959ca:53ed751d:7b3b40ba
Creation Time : Sun Apr 17 13:24:05 2005
Raid Level : raid1
Raid Devices : 2
Total Devices : 2
Preferred Minor : 0
Update Time : Fri May 13 16:52:37 2005
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Checksum : 1dcab069 - correct
Events : 0.482221
Number Major Minor RaidDevice State
this 0 22 1 0 active sync
/dev/.static/dev/hdc1
0 0 22 1 0 active sync
/dev/.static/dev/hdc1
1 1 3 65 1 active sync
/dev/.static/dev/hdb1
I'm not sure how this happen but I've come up with a couple of
possibilities that happen several months ago.
1. I migrated these disk from a previous test box for this server. I
may have messed on the initial install into the new box.
2. I replaced hdb1 as hdc1 when doing some maintenance.
In any case LVM recognized the UUID of one of disks and continued
normally.
Now I'm try to fix the situation. All the data on the disks are backup
so I could just start fresh but I would like to repair the situation if
I can. Here is the steps I've come up with. Please check them out for
pitfalls etc or missing commands.
Outline:
To fix the LVM, I will treat the situation as if I am migrating the
disks to a new system. Instead of moving drives I will be repairing raid.
To fix Raid I need to determine which disk LVM has been using then
restart the RAID with that disk then add the second disk as a spare.
Detail:
1. Umount file systems
# unmount /backup
# unmount /share/ftp
# unmount /share
2. Mark Volume Group as inactive
# vgchange -an data
3. Export volume Group
# vgexport data
4. Mount Disk and examine contents for recent data
# mount /dev/hdb1 /mnt/hdb
# mount /dev/hdc1 /mnt/hdc
5. Restart array with devices with most recent data
# mdadm -A /dev/md0 /dev/hdb1 or /dev/hdc1
(will this start the array degraded or do I need to create a new array
with mdadm -C /dev/md0 --level=1 --raid-devices=/dev/hdb1 missing)
6. Add second devices as spare
# mdadm /dev/md0 --add /dev/hdc1 or /dev/hdb1
7. Fix LVM (this is assuming that pvscan now recognizes PV /dev/md0 as
being apart of VG data
# vgimport data
# vgchange -ay data
# mount /share
# mount /share/ftp
# mount /backup
8. Set up mdadm in monitor mode and have a beer!
Thanks for the help in advance
Colin
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