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Date:      Mon, 1 Sep 2008 15:36:29 -0700
From:      Jeremy Chadwick <koitsu@FreeBSD.org>
To:        Kevin Oberman <oberman@es.net>
Cc:        Derek =?iso-8859-1?B?S3VsacU/c2tp?= <takeda@takeda.tk>, Michael <freebsdports@bindone.de>, freebsd-stable@freebsd.org
Subject:   Re: bin/121684: : dump(8) frequently hangs
Message-ID:  <20080901223629.GA18346@icarus.home.lan>
In-Reply-To: <20080901213856.GA17155@icarus.home.lan>
References:  <200809011336.m81Da5BT046532@lava.sentex.ca> <20080901160013.0005F4500F@ptavv.es.net> <20080901213856.GA17155@icarus.home.lan>

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On Mon, Sep 01, 2008 at 02:38:56PM -0700, Jeremy Chadwick wrote:
> The problem was that UFS2 snapshot generation, over time, becomes
> slower and slower to generate (this is what dump does on UFS2 systems,
> with or without the -L flag), and is a known design issue.

Clarification: dump on UFS2 (without -L flag) will NOT generate a
snapshot, but emits a nasty message telling you to use -L on live
filesystems which are mounted r/w.

I'm wondering if people experiencing this problem are using the -L flag
or not (I'm betting most are).  If you are, try removing it and see if
things improve.  But if I remember correctly, there's also a risk
involved with this: not generating a snapshot on UFS2 means your dump
could actually contain "half-written" files (e.g. when you recover, you
might only have a partial file for something that was being written at
the time of dump).

-- 
| 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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