UFS2 Snapshots in 6.1-Beta4 - Confirmed Problems
Kris Kennaway
kris at obsecurity.org
Thu Mar 23 18:57:24 UTC 2006
On Thu, Mar 23, 2006 at 10:42:59AM -0800, John Kozubik wrote:
>
>
> On Thu, 23 Mar 2006, Kris Kennaway wrote:
>
> > On Tue, Mar 21, 2006 at 01:36:44AM -0800, John Kozubik wrote:
> >
> > > First, I have confirmed that a filesystem with multiple snapshots that
> > > undergoes multiple, rapid deletions of files, will cause the system to
> > > hang. I have witnessed this before, but had not confirmed it or
> > > documented it in a PR. Now that I have confirmed this behavior, I have
> > > documented it in: kern/94769
> >
> > I ran a (completion of) your script in a loop for about 24 hours and
> > it didn't deadlock. This may be because there was a second set of
> > fixes that was merged in to 6.x a day or two ago. Are you able to
> > confirm whether they indeed fixed this problem?
>
> What ratio of snapshots / rms did you run ?
3/3, as you suggested.
> I reproduced this easily on
> 6.0-RELEASE and 6.1-BETA4. I am traveling right now and cannot test on
> anything newer. Can you try it on one of the two above, confirm for
> yourself that it manifests itself, and then compare that to what you see
> on whatever newer code you have ? If it is fixed, that's great.
Not right away, unfortunately.
> > > Second, kern/92292 is still a problem. I have reproduced this error in
> > > 6.1-BETA4 (and have seen it happening since 5.1). The (small) difference
> > > is that the cp process seems to stick in the flswai state instead of
> > > biowr.
> >
> > I'll test this one next.
>
>
> Great - thanks. It's less urgent, as running a md-backed FS on a
> snapshotted FS is less common, and easily avoided. The big fish are the
> rm problems (you can't avoid deleting things) and the "full filesystem"
> problems, since there is always a danger of that.
Yeah, the full filesystem bugs are a big pain, but as I mentioned
probably nothing can be done in time for 6.1 since it's a pretty big
job.
Kris
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