On Thu Nov 12, 2009 at 10:03:51PM +0100, Janek Kozicki wrote:

Hi,

I have an old debian etch backup server. It has 5 drives in raid4.
I want to add a sixth drive to jump to raid6. I don't want to upgrade
debian etch, because the server is working real fine, and doing an
upgrade would be too much problems.

And so my plan is to get some liveCD with 2.6.31 (or maybe 2.6.32 ?).
Connect the sixth drive, boot liveCD, perform the migration:

mdadm --add /dev/md2 /dev/sdd3
mdadm --grow /dev/md2 --level=raid6 --raid-disks=6

Then reboot back into linux 2.6.24.

Will this work?

Will 2.6.24 understand such raid6 ?

I don't think so, no.  It's not a standard RAID6 (as all the Q parity is
on a single disk) so I think you need the newer kernel to understand it.

Cheers,
    Robin
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