On Sun, Mar 22, 2009 at 3:15 AM, Max Amanshauser
<linux-raid@xxxxxxxxxxxxxxxxx> wrote:
>
> On Mar 22, 2009, at 4:15 AM, Erik Boettcher wrote:
>
>> Indeed recreating seems like my only option now. I'd like to ensure
>> the right creation order, so I'd like to ask for some help. Attached
>> is the output of 'mdadm -Evvvv /dev/sd{a,b,c,d,e}3' Any help
>> restoring this array is greatly appreciated!
>> <mdadmEout>
>
>
>
> I had the same problem recently and solved it relatively pain-free.
>
>
> Basically what I did was:
>
> *) Find out where the old superblocks are located and backup them with dd,
> just in case. Ideally you should backup all of the disks entirely (if they
> have errors, use dd_rescue and do the following on healthy disks).
Hmm, I can't back up the disks but I'm trying to get the superblocks.
I can't find where they're located to copy them!
>
> *) Recreate with mdadm and the same options that were used when creating the
> raid in the first place, with one device declared missing.
> "mdadm --create /dev/md0 -e 0.90 -c 32 -p left-asymmetric -l 5 -n 5
> /dev/sdc3 /dev/sdd3 /dev/sde3 /dev/sdb3 missing" sounds about right in your
> case. I'd find out what the difference between 0.88 and 0.90 superblocks is,
> though. If you have devices with errors you should declare the most broken
> one missing, of course. And make absolutely sure that the options are
> correct or you will overwrite innocent data. The device order is not so
> important, since you can change it in subsequent recreate attempts without
> breaking anything.
Is the order that mdadm --query provides more correct? I guess I'll find out....
>
> *) Try to read-only mount the array, and/or use dumpe2fs (if you have
> ext2/3). If it works, hurray. If not, recreate again with a different device
> order. Ultimately you will probably have to e2fsck to correct the damage.
LLVM is being used here, so I'll have to make sure vgscan etc don't write...
>
>
> I got the correct device order on the second attempt and lost only 150kB due
> to hard disk errors. Guess I was lucky.
>
> --
> Good luck,
Thanks, I need it.
> Max.
Erik
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