reshape raid5 to raid6

[Michael Ole Olsen <gnu@gmx.net>]

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Is it possible to reshape my /dev/md0 raid5 into raid6?

I found the following recipe in the docs:
mdadm --create /dev/md0 -l6 -n4 /dev/sdb1 /dev/sdc1 /dev/sdd1 missing

I have 9 disks in my raid5, would i then do:
[1] mdadm --create /dev/md0 -l6 -n10 /dev/sda /dev/sdb ... missing

i.e. only the first 9 drives and then hot add a new device to get it to
reshape and add the extra parity to all drives?

mdadm --add /dev/md0 /dev/sdk ?

I would guess  command [1] would give problems as md0 is an active array
will it work if i --stop the array first so that i can reshape to raid6?

I couldn't really find much information on this, some say it is impossible
without recreating the array? (So i ask here first before i try, as I dont
want to risk my data, even though I have backups of the important
data)

Any advice would be nice

/Michael Ole Olsen

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