[Lustre-discuss] How to estimate the time for e2fsck on OST

[Andreas Dilger]

On Aug 04, 2009  22:47 +0000, Peter Grandi wrote:
> Andreas Dilger wrote:
> adilger> Putting 4 OSTs on a single disk doesn't make sense.
> adilger> A single OST can be up to 8TB, and if you have multiple
> adilger> OSTs on the same disk(s) it will cause terrible
> adilger> performance problems due to seeking.
> 
> Uhm, not exactly, that's a quick but simplistic answer: things
> are more complicated than that.

[lengthy discussion removed]

> Note 3: in many if not most (just a guess) Lustre installations the
> "disk" is actually a SAN RAID pool, and each OST is a LUN of that
> SAN RAID pool, and that LUN is in effect a slice of a partition off
> each disk. Now this is may not be at all what Lustre should be about :-).

This is what will happen with any RAID that I'm aware of, and is
specifically what I was referring to when I said "disk" instead
of "LUN".

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.