(original article)

Re: Converting RAID5 to RAID6 and other shape changing in md/raid

26 July 2010, 03:00 UTC

Yes it is possible, but you have to go through a slightly round-about route. I have made a note to look at fixing it for a future release.

You need to first

mdadm --grow /dev/md2 --size=max

and then try

mdadm --grow /dev/md2 --raid-devices=4

That won't work but will tell you to use "--grow --array-size=" to reduce the array size. It will tell you what size is needed. So

mdadm --grow /dev/md0 --array-size=whatever
mdadm --grow /dev/md2 --raid-devices=4

That should do what you want.