[Lustre-discuss] slow journal/commitrw on OSTs lead to crash

[Brian J. Murrell]

On Wed, 2009-04-08 at 13:51 -0600, Daniel Leaberry wrote:
> 
> I ran into a similar scenario with lustre when I hit 80% full as well.
> Exact same problem with journal commits and disks seemingly unusable.
> iostat on the disks (DDN 9500 array) shows huge numbers of small reads.
> Almost like the disk is being scanned.

Interesting.  It's probably worth mentioning the historical (anecdotal
at least) warning that as ext2/3 filesystems get full, they become less
efficient.  That's not surprising as a filesystem certainly can fall
into the category of resources that become less efficient as they become
more full due to the overhead of finding suitable allocations.

I don't know enough about the internals of ext2/3/4 to comment directly
on the design decisions that led to this or how much of those problems
still exist today in ext4.  Perhaps one of our ext3/4 experts can
comment.

Would certainly make for an interesting benchmarking test.

b.

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