Hi,
I used to have the following array:
# mdtab entry for /dev/md0
/dev/md0 raid5,128k,0,93fa4522 /dev/hda3 /dev/hdb1 /dev/hdc1 /dev/hdd1
This ran on linux 2.2.17 and raidtools 0.42. When upgrading the kernel to 2.4.22
and raid-tools 0.90 I understood that it would be necessary to run mkraid --upgrade
on the device. So I run it on the following raidtab:
/etc/raidtab:
raiddev /dev/md0
raid-level 5
nr-raid-disks 4
nr-spare-disks 0
persistent-superblock 1
parity-algorithm left-symmetric
chunk-size 32
device /dev/hda3
raid-disk 0
device /dev/hdb1
raid-disk 1
device /dev/hdc1
raid-disk 2
device /dev/hdd1
raid-disk 3This one was copied straight from Software-RAID HOWTO, unfortunately I noticed
only afterwards that the chunk-size was different than it was before. Anyway,
mkraid seemed to convert the array; it printed out many pages of information
which I didn't analyze further, but apparently it left the raid in a somehow
bad state, because:
# raidstart /dev/md0 /dev/md0: Invalid argument
# cat /proc/mdstat Personalities : [raid5] read_ahead not set unused devices: <none>
I learned that mdadm would apparently be a good tool for analysing the situation,
but I had no success there:
# mdadm --examine /dev/md0 mdadm: /dev/md0 is too small for md
Trying to --upgrade with the correct chunk 128kb size set in /etc/raidtab just prints:
handling MD device /dev/md0 analyzing super-block disk 0: /dev/hda3, 78935377kB, raid superblock at 78935296kB array needs no upgrade mkraid: aborted, see the syslog and /proc/mdstat for potential clues.
And trying to go back to kernel 2.2.17 and raidtools 0.42 causes the following havoc in
/etc/init.d/raid start:
Adding md devices. /dev/md0: Invalid argument Some of the RAID devices have errors: Checking "md0": ckraid: aborted ckraid version 0.36.4 parsing configuration file handling MD device /dev/md0 analyzing super-block disk 0: /dev/hda3, 78935377kB, raid superblock at 78935296kB disk 1: /dev/hdb1, 80035798kB, raid superblock at 80035712kB disk 2: /dev/hdc1, 80035798kB, raid superblock at 80035712kB disk 3: /dev/hdd1, 80035798kB, raid superblock at 80035712kB reading raid superblock unsupported raid array version 0.90.0 /dev/md0: Invalid argument WARNING: unrecovered RAID errors!
So apparently the superblocks _are_ there but the kernel just cannot read them.
Is there any way to correct the situation without remaking the array?
I'd just like to know if the data is definitely gone forever after specifying
the wrong chunk size, or is there still hope to recover it.
Any help would be greatly appreciated!
-J
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