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

[Kris Kennaway]

On Mon, May 21, 2007 at 03:35:56PM -0500, Rick C. Petty wrote:
> On Mon, May 21, 2007 at 03:56:34PM -0400, Kris Kennaway wrote:
> > > 
> > > The one thing I *have* experienced is filesystems going nuts after
> > > filling them. Specifically I end up with a negative amount of space
> > > free, and as soon as you release more space df -h quickly reports the
> > > amount of free space dropping (you can see it interactively churning for
> > > a few secs) until it settles at some negative amount again and you're
> > > back to square one. This has happened once or twice in the past, but not
> > > recently. Not sure which release it did happen on; might have been 5.x.
> > 
> > Yeah, this was an old bug in the 5.x timeframe.  As far as I recall it
> > was fixed at some point in the past.
> 
> 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.

Kris