Quoting Carlos Carvalho <carlos@xxxxxxxxxxxxxx>:
jay@xxxxxxxxxxxxxxxxxxxxxxxxx (jay@xxxxxxxxxxxxxxxxxxxxxxxxx) wrote
on 20 April 2008 18:35:
>I had a single disk failure in a 3-disk RAID5 array recently, and have
>been trying to reassemble the array with the remaining devices, but am
>running into some issues.
>
>The failed disk died during synchronization into the array,
Did another one fail during the resync? If not you can try to
reassemble the array with only the 2 good disks using --force.
The array did fall offline shortly after the first failure, which
seemed unexpected; the two remaining disks (and controller) still seem
healthy (states 'clean' and 'active' respectively), just that they
refuse to assemble.
If a second disk failed you're in trouble. Since the array stopped at
the moment of the second failure, the two disks are still in sync.
Well, almost... You can then make an image of the second failed disk
on a good one and use --force to reassemble again. Then fsck...
This sounds good - the only filesystem mounted over the devices was
read-only at the time, so I'm hoping that the two good disks should
still be enough for some data recovery.
The only problem I see is that if I make a raw image copy of the
second disk, it will still have the incorrect 'slot' assignment in the
superblock. I suppose I could dd everything except the superblock -
but is there a mechanism to repair/recreate the superblock on a raw
disk?
The other idea I have in mind is to - after a backup - recreate the
array using the initial configuration (raid-level 5, num-devices 3,
etc), and hope that the array can pick itself up again.
Any thoughts much appreciated - thanks for helping out :)
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