From: Hugo Mills <hugo@carfax.org.uk>
To: Roger Binns <rogerb@rogerbinns.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Questions about multi-device behavior
Date: Thu, 18 Jul 2013 23:03:09 +0100 [thread overview]
Message-ID: <20130718220309.GD20517@carfax.org.uk> (raw)
In-Reply-To: <ks9ogo$8rg$1@ger.gmane.org>
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On Thu, Jul 18, 2013 at 02:59:58PM -0700, Roger Binns wrote:
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> On 18/07/13 13:05, Chris Murphy wrote:
> > Sounds like if I have a degraded 'single' volume, I can simply cp or
> > rsync everything from that volume to another, and I'll end up with a
> > successful copy of the surviving data. True?
>
> Not quite. I did it with cp -a. Because all the metadata survived, cp
> would create the target file, but then get an i/o error on opening/reading
> the source file. It would print an error message, but not delete the
> empty target file. Consequently I ended up with loads of zero length files
> I had to go in and delete afterwards.
The odds of having an undamaged file from that process are much
better for single than for RAID-0 (and aren't affected by having tools
which will cope better with IO errors -- although you'll get more of
each damaged file if you do). As the file size goes up, the odds of it
being damaged increase.
Hugo.
> I briefly looked for an rsync option to keep going on source i/o errors
> but didn't find one.
>
> Roger
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--
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk
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next prev parent reply other threads:[~2013-07-18 22:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-17 21:24 Questions about multi-device behavior Florian Lindner
2013-07-17 21:49 ` Chris Murphy
2013-07-18 2:00 ` Roger Binns
2013-07-18 17:33 ` David Sterba
2013-07-18 20:05 ` Chris Murphy
2013-07-18 21:59 ` Roger Binns
2013-07-18 22:03 ` Hugo Mills [this message]
2013-08-02 14:10 ` David Sterba
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