atxdavid
December 13th, 2011, 07:21 PM
A few weeks ago, I set up an old Pentium IV system with two 2TB SATA drives (/dev/sdb and /dev/sdc), configured in a RAID-1 array, with an LVM filesystem on top of it. The system boots off of a non-RAID, non-LVM /dev/sda. Then, over the weekend, I did the usual “sudo apt-get update” followed by “sudo apt-get dist-upgrade” to update my system (Ubuntu 10.04 LTS Desktop). Following a reboot, my LVM was no longer available, and my RAID showed “degraded.”
The Disk Utility in Ubuntu showed the following message:
Error assembling array: mdadm exited with exit code 1: mdadm: WARNING /dev/sdb1 and /dev/sdb appear to have very similar superblocks.
If they are really different, please --zero the superblock on one
If they are the same or overlap, please remove one from the list.
I never actually zeroed the superblock, but noticed that the RAID system was attempting to repair itself (via looking at /proc/mdstat).
I now find myself in the situation where the RAID array appears to be intact. Below is the output of “cat /proc/mdstat”:
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md_d0 : active raid1 sdb[0] sdc[1]
1953513472 blocks [2/2] [UU]
unused devices: <none>
So the RAID array looks fine. The LVM partitions appear to still be there too. Below is the output of sfdisk –l:
Disk /dev/sda: 30401 cylinders, 255 heads, 63 sectors/track
Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sda1 * 0+ 29650- 29651- 238164992 83 Linux
/dev/sda2 29650+ 30401- 751- 6031361 5 Extended
/dev/sda3 0 - 0 0 0 Empty
/dev/sda4 0 - 0 0 0 Empty
/dev/sda5 29650+ 30401- 751- 6031360 82 Linux swap / Solaris
WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util sfdisk doesn't support GPT. Use GNU Parted.
Disk /dev/sdb: 243201 cylinders, 255 heads, 63 sectors/track
Warning: The partition table looks like it was made
for C/H/S=*/81/63 (instead of 243201/255/63).
For this listing I'll assume that geometry.
Units = cylinders of 2612736 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sdb1 0+ 765633- 765634- 1953513560 8e Linux LVM
end: (c,h,s) expected (1023,80,63) found (513,80,63)
/dev/sdb2 0 - 0 0 0 Empty
/dev/sdb3 0 - 0 0 0 Empty
/dev/sdb4 0 - 0 0 0 Empty
WARNING: GPT (GUID Partition Table) detected on '/dev/sdc'! The util sfdisk doesn't support GPT. Use GNU Parted.
Disk /dev/sdc: 243201 cylinders, 255 heads, 63 sectors/track
Warning: The partition table looks like it was made
for C/H/S=*/81/63 (instead of 243201/255/63).
For this listing I'll assume that geometry.
Units = cylinders of 2612736 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sdc1 0+ 765633- 765634- 1953513560 8e Linux LVM
end: (c,h,s) expected (1023,80,63) found (513,80,63)
/dev/sdc2 0 - 0 0 0 Empty
/dev/sdc3 0 - 0 0 0 Empty
/dev/sdc4 0 - 0 0 0 Empty
WARNING: GPT (GUID Partition Table) detected on '/dev/md_d0'! The util sfdisk doesn't support GPT. Use GNU Parted.
However, the actual LVM information is nowhere to be found. Pvscan simply outputs “No matching physical volumes found.”
Is there a way to recover the data I had on these drives, or am I toast?
Thanks in advance.
The Disk Utility in Ubuntu showed the following message:
Error assembling array: mdadm exited with exit code 1: mdadm: WARNING /dev/sdb1 and /dev/sdb appear to have very similar superblocks.
If they are really different, please --zero the superblock on one
If they are the same or overlap, please remove one from the list.
I never actually zeroed the superblock, but noticed that the RAID system was attempting to repair itself (via looking at /proc/mdstat).
I now find myself in the situation where the RAID array appears to be intact. Below is the output of “cat /proc/mdstat”:
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md_d0 : active raid1 sdb[0] sdc[1]
1953513472 blocks [2/2] [UU]
unused devices: <none>
So the RAID array looks fine. The LVM partitions appear to still be there too. Below is the output of sfdisk –l:
Disk /dev/sda: 30401 cylinders, 255 heads, 63 sectors/track
Warning: extended partition does not start at a cylinder boundary.
DOS and Linux will interpret the contents differently.
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sda1 * 0+ 29650- 29651- 238164992 83 Linux
/dev/sda2 29650+ 30401- 751- 6031361 5 Extended
/dev/sda3 0 - 0 0 0 Empty
/dev/sda4 0 - 0 0 0 Empty
/dev/sda5 29650+ 30401- 751- 6031360 82 Linux swap / Solaris
WARNING: GPT (GUID Partition Table) detected on '/dev/sdb'! The util sfdisk doesn't support GPT. Use GNU Parted.
Disk /dev/sdb: 243201 cylinders, 255 heads, 63 sectors/track
Warning: The partition table looks like it was made
for C/H/S=*/81/63 (instead of 243201/255/63).
For this listing I'll assume that geometry.
Units = cylinders of 2612736 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sdb1 0+ 765633- 765634- 1953513560 8e Linux LVM
end: (c,h,s) expected (1023,80,63) found (513,80,63)
/dev/sdb2 0 - 0 0 0 Empty
/dev/sdb3 0 - 0 0 0 Empty
/dev/sdb4 0 - 0 0 0 Empty
WARNING: GPT (GUID Partition Table) detected on '/dev/sdc'! The util sfdisk doesn't support GPT. Use GNU Parted.
Disk /dev/sdc: 243201 cylinders, 255 heads, 63 sectors/track
Warning: The partition table looks like it was made
for C/H/S=*/81/63 (instead of 243201/255/63).
For this listing I'll assume that geometry.
Units = cylinders of 2612736 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sdc1 0+ 765633- 765634- 1953513560 8e Linux LVM
end: (c,h,s) expected (1023,80,63) found (513,80,63)
/dev/sdc2 0 - 0 0 0 Empty
/dev/sdc3 0 - 0 0 0 Empty
/dev/sdc4 0 - 0 0 0 Empty
WARNING: GPT (GUID Partition Table) detected on '/dev/md_d0'! The util sfdisk doesn't support GPT. Use GNU Parted.
However, the actual LVM information is nowhere to be found. Pvscan simply outputs “No matching physical volumes found.”
Is there a way to recover the data I had on these drives, or am I toast?
Thanks in advance.