reshape failure

[Tobias McNulty <tobias@caktusgroup.com>]

Hi,

I tried to start a reshape over the weekend (RAID6 -> RAID5) and was
dismayed to see that it was going to take roughly 2 weeks to complete:

md0 : active raid6 sdc[0] sdh[5](S) sdg[4] sdf[3] sde[2] sdd[1]
5860543488 blocks super 0.91 level 6, 64k chunk, algorithm 2 [5/5]
[uuuuu] [>....................] reshape = 0.0% (245760/1953514496)
finish=21189.7min speed=1536K/sec

The disk that contained the backup file began experiencing SATA errors
several days into the reshape, due to what turned out to be a faulty
SATA card.  The card has since been replaced and the RAID1 device that
contains the backup file successfully resync'ed.

However, when I try to re-start the reshape now, I get the following error:

nas:~# mdadm --assemble /dev/md0 --backup-file=md0.backup /dev/sdc
/dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh
mdadm: Failed to restore critical section for reshape, sorry.

Is my data lost for good?  Is there anything else I can do?

Thanks,
Tobias
--
Tobias McNulty, Managing Partner
Caktus Consulting Group, LLC
http://www.caktusgroup.com