Re: Raid 5 Recovery

[Redeeman <redeeman@metanurb.dk>]

On Sun, 2008-12-28 at 01:21 -0500, Erik Boettcher wrote:
> Hello everyone, I'm trying to recover a raid-5 array that suffered
> from a powerloss (and possibly de-seating of a SATA card that 3 out of
> the 5 drives were on).
> As far as I can tell, the drives themselves are still okay.
> At first this is what happened when I tried mounting it from a livecd:
> 
> md: Autodetecting RAID arrays.
> Bad version number 0.88 on sda3
> md: sda3 does not have a valid v0.90 superblock, not importing!
> Bad version number 0.88 on sdb3
> md: sdb3 does not have a valid v0.90 superblock, not importing!
> Bad version number 0.88 on sdc3
> md: sdc3 does not have a valid v0.90 superblock, not importing!
> md: Scanned 5 and added 2 devices.
> md: autorun ...
> md: considering sde3 ...
> md:  adding sde3 ...
> md:  adding sdd3 ...
> md: created md0
> md: bind<sdd3>
> md: bind<sde3>
> md: running: <sde3><sdd3>
> raid5: device sde3 operational as raid disk 2
> raid5: device sdd3 operational as raid disk 1
> raid5: not enough operational devices for md0 (3/5 failed)
> RAID5 conf printout:
>  --- rd:5 wd:2
>  disk 1, o:1, dev:sdd3
>  disk 2, o:1, dev:sde3
> raid5: failed to run raid set md0
> md: pers->run() failed ...
> md: do_md_run() returned -5
> md: md0 stopped.
> md: unbind<sde3>
> md: export_rdev(sde3)
> md: unbind<sdd3>
> md: export_rdev(sdd3)
> md: ... autorun DONE.
> 
> At this point I sought help on ##linux on freenode, running this:
> mack ~ # mdadm -D /dev/md0
> mdadm: md device /dev/md0 does not appear to be active.
> mack ~ # mdadm --assemble /dev/md0 --scan
> mdadm: superblock on /dev/sdc3 doesn't match others - assembly aborted
> mack ~ # mdadm -A --force /dev/md0
> mdadm: superblock on /dev/sdc3 doesn't match others - assembly aborted
> mack ~ # mdadm -A --force /dev/md0 /dev/sd{a,b,c,d,e}3
> mdadm: superblock on /dev/sdd3 doesn't match others - assembly aborted
> 

Im by no means an expert in this, but i think you need to force an
assembly of all the disks..

but, wait for the opinions of other more knowledgable people in this
area...


> At this point I said WOAH -- time to stop with the freenode help --
> I'm hoping I didn't cause too much more damage there...
> 
> I'm trying to get this array up and any help would be greatly
> appreciated -- I don't want to do anything more to write to the drive
> without expert advice.
> Many thanks,
> Erik Boettcher
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