Re: change from raid 5 to raid 6 interrupted

[John Robinson <john.robinson@anonymous.org.uk>]

On 22/04/2011 15:49, Raphael Müller wrote:
> last week i tried to grow my raid 5 with 4 disks to a raid 6 with 5
> disks. accidentialy i dropped the powersource and the resync process
> stopped.
>
> i could start the nas with a rescue stick, but i still wasnt' able to
> complete the resync. there are some output from different commands
> (examine and assemble tries)
>
> i'm very confused, because there stands active sync, but raid 6 and i
> think since it was very at the beginning, there was no data changed on
> the 4 raid 5 disks.
>
> what should i do? and is it possible to rebuild this array? luckily i
> have somewhere around 90% of the data backed up on another nas.

The end of the assemble output has the answer:
> mdadm:/dev/md1 has an active reshape - checking if critical section needs to be restored
> mdadm: Failed to find backup of critical section
> mdadm: Failed to restore critical section for reshape, sorry.
>       Possibly you needed to specify the --backup-file

You need to manually re-issue the assemble command, and specify the 
--backup-file you gave when you started the --grow. That should get the 
array assembled and the reshape running again.

Cheers,

John.

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