System hanging during dump
koitsu at FreeBSD.org
Wed Oct 15 03:53:39 PDT 2008
On Wed, Oct 15, 2008 at 08:48:09PM +1100, Peter Jeremy wrote:
> On 2008-Oct-15 02:08:48 -0700, Jeremy Chadwick <koitsu at FreeBSD.org> wrote:
> >On Wed, Oct 15, 2008 at 07:58:43PM +1100, Peter Jeremy wrote:
> >> On 2008-Oct-15 01:35:38 -0700, Jeremy Chadwick <koitsu at FreeBSD.org> wrote:
> >> >On Wed, Oct 15, 2008 at 07:24:28PM +1100, Peter Jeremy wrote:
> >> >> Last night, I attempted a full, compressed backup of my 181GB /home
> >> >> (on a PATA disk) to a remote system. The backup started at 2159 and
> >> >> everything appeared normal until about 0040 when the system became
> >> >> non-responsive and this lasted until the dump completed at 1033. This
> >> >> is the first full backup of /home I've made for several years (due to
> >> >> lack of space).
> >> ...
> >> >It's a known problem documented in my Wiki -- see "dump/restore". Note
> >> >the part about UFS2 snapshot generation. I'm almost certain this is
> >> >what you're describing.
> >> * UFS2 snapshot generation (mksnap_ffs, dump -L) takes too long; system is unusable during this time
> >> In my case, snapshot creation took ~4 minutes. The system was
> >> running normally for 2.6 hours after snapshot creation completed
> >> before it froze.
> >Did you read the References, including the one from myself?
> Yes. In my case, dump started and ran mksnap_ffs. About 4 minutes
> later, actual dumping started and data streaming continued for about
> 12.6 hours. The system froze about 2.6 hours into the dump (after
> dump had written about 31GB).
> >Snapshot generation in some cases took only minutes, but *removal* of
> >the generated the snapshot took 1.5 hours or more, hanging the system
> >until the removal was complete.
> Based on progress reports from both dump and my fifo process, the
> snapshot removal began about 10 hours _after_ the system froze
> (during this time, dump wrote about 143GB). Given the timeline,
> it's fairly clear that neither mksnap_ffs nor the 'rm snapshot'
> were running at the time the system froze. I am therefore quite
> confident that the problem I saw is not related to either creation
> or removal of snapshots.
> I have been using FreeBSD snapshots for many years and am quite
> familiar with their quirks. I have never seen this particular
> problem before. (And FWIW, I _am_ using Doug Ambrisko's patch to
I don't doubt your seniority or technical skill set. I was simply
offering information that appeared relevant.
Sorry for the noise and incorrect correlation.
| Jeremy Chadwick jdc at parodius.com |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
| Making life hard for others since 1977. PGP: 4BD6C0CB |
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