UFS2 Snapshots in 6.1-Beta4 - Confirmed Problems.

Kris Kennaway kris at obsecurity.org
Thu Mar 23 21:39:44 UTC 2006

On Thu, Mar 23, 2006 at 10:16:47PM +0100, Julien Gabel wrote:
> > While we're on the topic of snapshots, I recently posted this follow-up to
> > the PR kern/66270 "[hang] dump causes machine freeze"
> >> I wonder what is the status of this PR?
> >>  I seem to have the same problem with 5.3-RELEASE.
> >>
> >>  Before this started, system worked nicely for more than a year and then
> >> it
> >>  started to hang during dump (seemingly just after mksnap_ffs) first
> >>  intermittently and now reproducibly (might increase in data size be a
> >>  factor? though disk is only about 18% full).
> >>  Originally it hanged and console had complains about increasing
> >>  PMAP_SHPGPERPROC and maxproc.
> >>  After some talk in freebsd-fs, I adjusted these parameters and now it
> >> just hangs without complaining =((
> >>
> >>  Any suggestions?
> > In addition to this PR, I found a couple of similar threads in different
> > lists but they all just have some initial talk and preliminary analysis,
> > and then it just stops. Was that snapshot problem fixed or is it the same
> > as we are talking now? I can't believe I am the only one in almost 2
> > years who is (trying to be) doing automated backups...
> > So, if it was fixed, when (which version)? If not, then when it might be
> > and -- in the meantime -- is there any workaround for backups? (The system
> > is the production server on the colocation so doing backups in single-user
> > mode is not practical).
> Interesting.  I used dump/restore without problem on i386 using a file
> system of 120Go.  I swiched two weeks ago on amd64 using a file system of
> 260Go and encountered the very same behaviour (hang, freeze).  Don't know
> if it is related to the new processor architecture or the bigger fs size,
> but i didn't observe this hang on smallest file system before.
> Because i am a big fan of dump, i currently choose to use it without the
> '-L' switch, back to the old (classical?) behaviour, i.e. not doing a
> snapshot before doing the dump.  It is always better than not having
> complete system backup at all (YMMV, though).
> I am currently running 6.1-PRERELEASE build Wed Mar 22 03:55:42 CET 2006.

Let us know if it recurs with your updated kernel.


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