2009/7/13 Domas Mituzas <midom.lists(a)gmail.com>om>:
> Precis: if the file system is very busy (being
hammered) *and* it's
> over 85% full, the block allocator can get stuck trying to work out
> the *very best* allocation rather than one that'll do and let it get
> on with other work. To the point where you see CPU go through the
> roof, with 80% system CPU and a very unresponsive system. You can't
> stop this without rebooting the box.
This is exactly what we're seeing, except that we
could get out of it
by dropping older snapshots.
Yeah - cutting down how full the file system is.
> Sun acknowledged it as a bug and it'll be
fixed in a future release;
> they gave us a hotpatch. The workaround? Keep the ZFS filesystem in
> question under 70% full ...
:-)
hehehehehe, 'the heck beaten out of it' sounds like what we tend to do
to our systems at wikimedia ;-)
It's useful testing, and you can be sure Sun will be interested in
your results in detail, we're a reasonably famous site! A coworker
spoke to the Sun kernel engineer tearing his hair out over this one
...
I fear the answer re: ZFS is to some extent "don't do that then" until
it's fixed. Of course, you want snapshots. It's a tricky one.
- d.