On 28/06/2012 14:06, Костырев Александр Алексеевич wrote:
- RAID1 pairs, plus some kind of intelligent overlay filesystem, eg
md-linear+XFS / BTRFS. With the filesystem aware of the underlying
arrangement it can theoretically optimise file placement and
dramatically increase write speeds for small files in the same manner
that RAID-0 theoretically achieves. (However, still no protection
against "silent" single drive corruption unless btrfs perhaps adds this
in the future?)
not only "silent" single drive corruption problem but as I stated in start of
topic - crash of first pair.
Bad things are going to happen if you loose a complete chunk of your
filesystem. I think the current state of the world is that you should
assume that realistically you will be looking to your backups if you
loose the wrong 2 disks in a raid1 or raid10 array.
However, the thing which worries me more with multidisk arrays is
accidental disconnection of multiple disks, eg backplane fails, or a
multi-lane connector is accidently unplugged. Linux MD raid often seems
to have the ability to reconstruct arrays after such accidents. I don't
have more recent experience with hardware controller arrays, but I have
(sadly) found that such a situation is terminal on some older hardware
controllers...
Interested to hear other failure modes (and successful rescues) from
RAID1+linear+XFS setups?
Cheers
Ed W
