Date: Wed, 15 Oct 2008 03:53:38 -0700 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Peter Jeremy <peterjeremy@optushome.com.au> Cc: freebsd-stable@FreeBSD.org Subject: Re: System hanging during dump Message-ID: <20081015105338.GA75226@icarus.home.lan> In-Reply-To: <20081015094809.GG26536@server.vk2pj.dyndns.org> References: <20081015082428.GE26536@server.vk2pj.dyndns.org> <20081015083538.GA72190@icarus.home.lan> <20081015085843.GF26536@server.vk2pj.dyndns.org> <20081015090848.GA72852@icarus.home.lan> <20081015094809.GG26536@server.vk2pj.dyndns.org>
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On Wed, Oct 15, 2008 at 08:48:09PM +1100, Peter Jeremy wrote: > On 2008-Oct-15 02:08:48 -0700, Jeremy Chadwick <koitsu@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@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 > ffs_snapshot.c). 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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