reboot during reshape: superblock incorrect, cannot assemble

reboot during reshape: superblock incorrect, cannot assemble

[Joris]

Hello,


While expanding a raid6 array from 4 to 5 drives, I rebooted (got
impatient) at arround 9% done.
After this reboot I cannot re-assemble the array: "mdadm: superblock
on /dev/sde2 doesn't match others - assembly aborted".
It always complains about the superblock of the first member
specified, re-ordering or excluding members offers no avail.

According to mdadm's examine, everything except checksum appears
identical (magic, version, uuid, reshape pos, events).

Various people suggest wiping the superblocks and re-creating the
array. Is this the best option?
Will this work with an array that is being rebuild/reshaped? Anything
else I could od?



Somewhat related: my raid version on that array is now somehow
00.91.00, grub2 (at least the last release) verifies for 90 and will
refuse to install (even if grub does not use the array, it seems). I'm
just going to remove the check on the code and recompile.


Thanks in advance,
Joris

Re: reboot during reshape: superblock incorrect, cannot assemble

[Mikael Abrahamsson]

On Tue, 17 Aug 2010, Joris wrote:

> Various people suggest wiping the superblocks and re-creating the
> array. Is this the best option?

Do not do this, since you were reshaping it'll break "everything".

You didn't provide what version of kernel and mdadm you were using, I 
suggest trying with 3.1.2 or newer at least, 3.1.3 preferrably.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se

Re: reboot during reshape: superblock incorrect, cannot assemble

[Joris]

2010/8/17 Mikael Abrahamsson <swmike@swm.pp.se>:
> On Tue, 17 Aug 2010, Joris wrote:
>
>> Various people suggest wiping the superblocks and re-creating the
>> array. Is this the best option?
> Do not do this, since you were reshaping it'll break "everything".
Phew. Dodged a bullet there - thanks!

> You didn't provide what version of kernel and mdadm you were using, I
> suggest trying with 3.1.2 or newer at least, 3.1.3 preferrably.

I'm running mdadm 2.6.7.1 on 2.6.32 (Ubuntu lucid during recovery) -
and the array was used before with 2.6.7.2-3 on 2.6.26 (Debian
Stable); all 64 bit.

I'll start by getting the recommended version, then try to re-assemble?


Regards,
Joris

Re: reboot during reshape: superblock incorrect, cannot assemble

[Joris]

> I'm running mdadm 2.6.7.1 on 2.6.32 (Ubuntu lucid during recovery) -
> and the array was used before with 2.6.7.2-3 on 2.6.26 (Debian
> Stable); all 64 bit.
>
> I'll start by getting the recommended version, then try to re-assemble?

I hit send too soon; 3.0.3 starts the array right away, fantastic!

note: should someone get in a similar situation: get the debian squeeze deb.


Now to teach grub about version 0.91 and I'm back in business.


Thanks Mikael,
Joris

Re: reboot during reshape: superblock incorrect, cannot assemble

[John Robinson]

On 17/08/2010 22:19, Joris wrote:
> Now to teach grub about version 0.91 and I'm back in business.

Version 0.91 means 0.90 + reshaping, mdadm that support reshaping mark 
0.90 arrays that are undergoing reshaping with version 0.91 so older 
mdadm that don't do reshaping don't try to start it. If your reshape is 
now restarted, mdadm will change the metadata version back to 0.90 when 
the reshape is finished.

Cheers,

John.