On Thu, 16 Jan 2014 22:03:00 +0100 den Hoog [off-list ref] wrote:

Hi Neil

can you try to make 'missing' working for imsm?

probably not on the short list of things to do, but if you are willing
to help me out, I'll appreciate it much!

Hi Dennis,

it seems that "missing" already works with IMSM.  I thought I remembered that
it didn't, but I was wrong.

So you should be able to create the raid0 using the first parts of the
devices, then create the RAID5.
When creating the RAID5, list the devices that should  make up the RAID5 in
the correct order.
So something like:

 mdadm -C /dev/md/imsm -e imsm -n 4 /dev/sd[bcde]
 mdadm -C /dev/md0 -l0 -n4 -c 128k -z 512G /dev/md/imsm
 mdadm -C /dev/md1 -l5 -n4 -c 128k missing /dev/sdc /dev/sdd /dev/sde

Then /dev/md1 should be your RAID5 array.

You should double-check the above command to make sure you agree with ever
part, and ask if there is anything that doesn't seem right.

NeilBrown