On Tue, Dec 29, 2009 at 1:31 PM, John Robinson
[off-list ref] wrote:

On 29/12/2009 12:08, Mikael Abrahamsson wrote:

quoted

On Tue, 29 Dec 2009, Jon Hardcastle wrote:

quoted

I run gentoo with kernel 2.6.22-gentoo-r8

to convert my 6 drive +1 spare raid 5 to a 7 drive raid 6?

No, you need at least kernel 2.6.32 to migrate from raid5 to raid6.

But if you don't want to run 2.6.32 permanently/on your live system, iirc you can just run it to do the migration, and once the migration and reshape have completed, you can go back to your production kernel.

Besides the kernel version issues, this type of migration is
definitely possible and should be safe. I just did one of these before
christmas - grew a 3 or 4-disk RAID-5 into a 6-disk RAID-6, all on
1.5TB drives. Lots of fun nail-biting moments watching /proc/mdstat!
As it turned out, the thing just started, went about its business, and
finished in a quiet and refined manner. Now my arrays are vast and
comfortably redundant ...

Just give yourself a set of big, physical reminders to update your
mdadm.conf when the reshape / relevel is done.

And you really, preferably ought to back your data up before you do
this. Even though the rearrangement will probably work just fine.

Merry everything!

-- Kristleifur