On 12/03/14 13:23, Raul Dias wrote: > 2014-03-12 6:12 GMT-03:00 David Brown <david.brown@xxxxxxxxxxxx>: > ... >> >> If you want to safely replace the disks in a raid5 array, the easiest >> way is to add a new disk (this can be an external USB disk if necessary) >> and re-shape to an asymmetric raid6 with parity Q on the new disk. Now >> you have an extra redundancy for safety. (Use asymmetric raid6 to avoid >> re-striping the existing disks.) > > Is there a solution for other RAID setups? 1,0,6,10? > > thanks > The whole idea of bumping up from raid5 to raid6 before maintenance is to improve the redundancy before you remove existing drives. It is not strictly necessary, but I think it is nice to have the extra safety. Hot replace makes it less important (since you don't remove the "old" drive until the new one is fully sync'ed). So for raid1, you would add a new mirror device, making a 3-way mirror instead of a 2-way one (I don't know off-hand if md raid allows this re-shape). Raid0 has no redundancy at all - so re-shape it to raid4 or asymmetric raid5 (which is equivalent) with parity on a new disk before doing the replacements. Raid6 already has two parities. You'll have to wait for Andrea Mazzoleni's great work on multi-parity raid to make it into mdadm and the kernel before you can add extra redundancy, but two disk redundancy is probably enough anyway (especially with hot replace). I think there are sever limits on the type of Raid10 reshapes you can do, so I don't think it is possible to add redundancy here. -- 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
