Date: Tue, 22 Jul 2003 22:58:44 +0100
From: Alasdair G Kergon <agk@uk.sistina.com>
To: dm-devel@sistina.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: [dm-devel] [RFC] File backed target for device-mapper
Message-ID: <20030722225844.T31325@uk.sistina.com>
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In-Reply-To: <1058908659.17049.9.camel@chtephan.cs.pocnet.net>; from christophe@saout.de on Tue, Jul 22, 2003 at 11:17:39PM +0200
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On Tue, Jul 22, 2003 at 11:17:39PM +0200, Christophe Saout wrote:
> I just wrote a dm target uses a file as backend instead of another block
> device.

Another suggestion:

  A target that always returns a block of zeros [or more generally,
  some other repeating pattern e.g. if the read goes beyond the end
  of your file - required to be multiple of sector size - it loops 
  round to the beginning; writes get dropped]

So you can easily create, for example a /dev/zero-like block device of
arbitrary size, which might be useful for replacing a lost disk that
contained a stripe if you want to read off the data from the other
stripes at correct offsets.

Alasdair
-- 
agk@uk.sistina.com
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