On Apr 11, 2013, at 11:52 AM, Keith Keller <kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > On 2013-04-11, Adam Goryachev <mailinglists@xxxxxxxxxxxxxxxxxxxxxx> wrote: >> >> I'm pretty sure this will work: >> 1) mdadm --manage /dev/md0 --add /dev/sdc1 # Add spare device >> 2) mdadm --grow /dev/md0 --level=1 --raid-devices=3 # Grow the array to >> three drive raid1 >> 3) mdadm --manage /dev/md0 --fail /dev/sdb1 # After the resync is >> finished, fail the old disk2 >> 4) mdadm --manage /dev/md0 --remove /dev/sdb1 # Now remove the old disk2 >> 5) # Now physically remove disk2. >> Repeat steps 1, 3, 4, 5 to replace disk1 with disk4. >> >> 6) mdadm --grow /dev/md0 --level=1 --raid-devices=2 # Reduce the array >> back to a two drive raid1 > > This seems like a reasonable way to replace a RAID1 device without > losing redundancy. Is there any way to accomplish the same sort of > thing in a RAID5 or 6? I am imagining something like, if I wanted to > replace device 0, I'd create a RAID1 with that device and the new > device, wait for that build to complete, then break the mirror and > remove the old device 0, so that the new drive becomes the new device 0. > I suppose one could create a RAID5 out of RAID1 components where each > RAID1 is initially degraded, but that seems inelegant. (I think this > option may have been suggested on this list at one point.) > > --keith > > -- > kkeller@xxxxxxxxxxxxxxxxxxxxxxxxxx > For a raid5 it's easy -- convert to a raid6 (and let it complete with an extra disk) for the conversion... then fail, remove, and add disks one at a time while retaining a raid5 level of redundancy. For a raid6 I don't think you have any such options. For a raid0 - convert to a raid4, add a parity disk and let it sync, then replace the non-parity disk and resync, last convert back to raid0 Of course all these options require you to have room for an extra disk ;) Sam-- 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
