Re: How trustworthy is the SE3310 RAID array?

On Sep 21, 12:37 am, Gary Mills <mi...@xxxxxxxxxxxxxxx> wrote:


It seems to me that the probability of three disks failing at the
same time is vanishingly small. Is there some bug in the SE3310
that could have caused this to happen after such a long time? Has
anyone else had this sort of a problem with an SE3310 or one of its
relatives?

One thing to do would be to have a look at the drives after they've
been swapped out (assuming Sun / whoever will let you keep them for a
bit). If they seem OK (after surface analysis in format for a few
days) then may be the 3310 is confused. If they're *not* OK then it's
not confused, but there's still a question as to why they all failed
at once. One obvious reason would be that they were all in the same
enclosure running from the same power, so if some nast event happened
(thermal or power) that could have taken them all out. That could also
be the 3310's fault of course. Or someone could have walked into it
or something (was work being done in the rack where it lives?), which
isn't really its fault.

Depending on RAID config it seems to me that there can be nasty
cascade mechanisms as well, For instance in a mirrored config if one
half of a mirror goes, the other half now has 2x as many reads to do,
so if it's on the way out this could cause it to die. In a RAID 5
config with a hot-spare, then if a drive fails, the spare comes in,
and now the parity must be rebuilt which means smashing the disks for
several hours (same in mirror but not so awful). I read somewhere
that a lot of R5 failures are because of this kind of thing.

--tim

.

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