lvm disappeared after disc replacement on raid10
- by user142295
here my problem:
I am running ubuntu 12.04 on a raid10 (4 disks), on top of which I installed an lvm with two volume groups (one for /, one for /home).
The layout of the disks are as follows:
Disk /dev/sda: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0003f3b6
Device Boot Start End Blocks Id System
/dev/sda1 * 63 481949 240943+ 83 Linux
/dev/sda2 481950 2910640634 1455079342+ fd Linux raid autodetect
/dev/sda3 2910640635 2930272064 9815715 82 Linux swap / Solaris
Disk /dev/sdb: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00069785
Device Boot Start End Blocks Id System
/dev/sdb1 63 2910158684 1455079311 fd Linux raid autodetect
/dev/sdb2 2910158685 2930272064 10056690 82 Linux swap / Solaris
Disk /dev/sdc: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Device Boot Start End Blocks Id System
/dev/sdc1 63 2910158684 1455079311 fd Linux raid autodetect
/dev/sdc2 2910158685 2930272064 10056690 82 Linux swap / Solaris
Disk /dev/sdd: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000f14de
Device Boot Start End Blocks Id System
/dev/sdd1 63 2910158684 1455079311 fd Linux raid autodetect
/dev/sdd2 2910158685 2930272064 10056690 82 Linux swap / Solaris
The first disk (/dev/sda) contains the /boot partition on /dev/sda1. I use grub2 to boot the system off this partition.
On top of this raid10 I installed two volume groups, one for /, one for /home.
This system worked well, I even exchanged two disks during the last two years. It always worked.
But not this time.
For the first time, /dev/sda broke. I do not know if this is an issue – I know I would have struggled anyways to overcome the problem with /boot installed on that disk and grub2 installed on the mbr of /dev/sda.
Anyways, I did what I always did:
start knoppix
fire up the raid
sudo mdadm --examine -scan
which returns
ARRAY /dev/md127 UUID=0dbf4558:1a943464:132783e8:19cdff95
start it up
sudo mdadm --assemble /dev/md127
fail the failing disk (smart event)
sudo mdadm /dev/md127 --fail /dev/sda2
remove the failing disk
sudo mdadm /dev/md127 --remove /dev/sda2
stop the raid
sudo mdadm -S /dev/md127
take out the disk
replace it with a new one
create the same partitions as on the failling one
add it to the raid
sudo mdadm --assemble /dev/md127
sudo mdadm /dev/md127 --add /dev/sda2
wait 4 hours
All looks fine:
cat /proc/mdstat
returns:
Personalities : [raid10]
md127 : active raid10 sda2[0] sdd1[3] sdc1[2] sdb1[1]
2910158464 blocks 64K chunks 2 near-copies [4/4] [UUUU]
unused devices: <none>
and
sudo mdadm --detail /dev/md127
returns
/dev/md127:
Version : 0.90
Creation Time : Wed Jun 10 13:08:46 2009
Raid Level : raid10
Array Size : 2910158464 (2775.34 GiB 2980.00 GB)
Used Dev Size : 1455079232 (1387.67 GiB 1490.00 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 127
Persistence : Superblock is persistent
Update Time : Thu Mar 21 16:27:40 2013
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : near=2
Chunk Size : 64K
UUID : 0dbf4558:1a943464:132783e8:19cdff95 (local to host Microknoppix)
Events : 0.4824680
Number Major Minor RaidDevice State
0 8 2 0 active sync /dev/sda2
1 8 17 1 active sync /dev/sdb1
2 8 33 2 active sync /dev/sdc1
3 8 49 3 active sync /dev/sdd1
However, there is no trace of the volume groups.
Rebooting into knoppix does not help
Restarting the old system (I actually replugged and re-added the failing disk for that – the system begins to start, but then fails to see the / partition – no wonder if the volume group is gone) does not help.
sudo vgscan, sudo vgdisplay, sudo lvs, sudo lvdisplay, sudo vgscan –mknodes
all returned No volume groups found.
I am completely at a loss.
Can anyone tell me if and how I can recover my data?
Thanks in advance!
