On Wed, June 24, 2009 8:27 pm, Michael Ole Olsen wrote: > Is it possible to reshape my /dev/md0 raid5 into raid6? If you are are using Linux 2.6.30, then you can echo raid6 > /sys/block/md0/md/level and it will instantly be sort-of-raid6. It is exactly like raid6 except that the Q blocks are all one the one drive, and drive that previously didn't exist. If you have a spare, it will start building the Q blocks on that drive and when it finishes you will have true raid6 redundancy, though possibly a little less than raid6 performance, as a real raid6 has the Q block distributed. When mdadm-3.1 is released, you will be able to tell the raid6 to re-stripe with a more traditional layout. This will take quite a while, but you can continue to use the array (though a bit more slowly) will it progresses. Of course you don't need to do that step if you don't want to. > > 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 If you did this, an the drives contained raid5 data, then that data would not be available on /dev/md0. NeilBrown > > 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 > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
