On Thu, Jan 10, 2013 at 12:19 PM, chris [off-list ref] wrote:

Hi Dave,

Thanks for the tip, this has gotten me further

# mdadm --assemble --scan
# cat /proc/mdstat
Personalities :
md127 : inactive sdd[1](S) sdb[0](S)
      4520 blocks super external:imsm

So atleast now it has created an array of sorts but it only has 2 out
of the 4 disks it should and also all disks appear to be marked as
spares.

Would I follow the same logic as typical mdadm recovery where I need
to create the array again with the right layout and disks in right
order and gain access to data without wiping it ?

Any advice what direction to go in from here?

Backup the disks you have if possible.

Don't recreate the array with all 4 disks be sure to specify a missing
slot.  With mdadm-3.2.5 you do have support for creating imsm arrays
with 'missing' slots [1].  Then you can test some recreations to see
if you can find data.

At a minimum you know that sdb and sdd are in slot 2, 3, so the
question is finding a good candidate for slot 0, or 1.  It's a bit
concerning that the superblocks for those have been lost, or those
disks weren't moved over?  You can look for serial numbers in
/dev/disks/by-id.

--
Dan

[1]: http://marc.info/?l=linux-raid&m=131432484118038&w=2