VERY frustrated with FreeBSD/UFS stability - please help or comment...

[Kris Kennaway]

On Mon, May 21, 2007 at 05:12:32PM -0500, Rick C. Petty wrote:
> On Mon, May 21, 2007 at 04:39:39PM -0400, Kris Kennaway wrote:
> > On Mon, May 21, 2007 at 03:35:56PM -0500, Rick C. Petty wrote:
> > > 
> > > Hmm, this recently happened to me in 6.2-STABLE.  I was unable to replicate
> > > it so filing a PR was pointless.  What I saw happen was that /usr filled up
> > > completely (I caught it before it hit 100% full, but watched helplessly as
> > > it switched from time to space optimization).  I even did a "du -hd0 /usr"
> > > and saw it only using about 20% of the file system.  lsof and fstat weren't
> > > terribly helpful.  After shutting down to single-user mode, I saw it full
> > > even though I deleted a lot of superfluous files, and du/df differences
> > > were still present.  I restarted and fsck cleaned up the 80% "used" space,
> > > stating the superblock free maps were incorrect, which explains the
> > > discrepency.  Why it happened, I'm still baffled.
> > 
> > OK, it may be that the bug is still around in some form, or it could
> > be a different issue.  One thing to check is whether you have a
> > snapshot active, because this will cause a very similar behaviour.
> 
> I don't use snapshots, except for bgfsck, which wasn't necessary because
> everything preened clean.
> 
> Like I said, it would be difficult to chase down.  I should probably just
> enable kernel DDB in case it happens again.

Yeah, if you can force a dump when something like this happens then it
may help to track it down.  Sometimes it is hard to reconstruct the
sequence of events leading to such a point though.

Kris