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From: Chris Samuel <chris@csamuel.org>
To: linux-btrfs@vger.kernel.org
Subject: Re: btrfs-convert fails
Date: Tue, 02 Nov 2010 11:43:11 +1100	[thread overview]
Message-ID: <4CCF5E9F.1040001@csamuel.org> (raw)
In-Reply-To: <AANLkTi=qwtEwBTxsqEBzQ78QA852wh9RDG-HNmABpj22@mail.gmail.com>

On 01/11/10 23:20, cwillu wrote:

> Problems resulting from powerloss should be limited to faulty hardware
> (in which case you're screwed regardless of the filesystem) and lack
> of barrier support (which should show up in dmesg soon after the first
> write goes to disk).

Note that for until 2.6.31 the DM layer didn't support barrier
operations fully, according to this email:

http://www.spinics.net/lists/linux-ext4/msg15789.html

# Barrier infrastructure started to get added to the DM
# core in 2.6.30, see: http://git.kernel.org/linus/af7e466a1ace
#
# But barriers were not enabled for all DM targets (_except_
# dm-multipath) until 2.6.31.  So 2.6.31's dm-crypt does support
# barriers, see: http://git.kernel.org/linus/647c7db14ef9
#
# If the underlying device(s) support barriers DM should
# faithfully pass them on (again except for dm-multipath).
# Also, requests with barriers that result in -EOPNOTSUPP
# are retried without the barrier, see:
# http://git.kernel.org/linus/51aa32284958

cheers,
Chris
-- 
 Chris Samuel  :  http://www.csamuel.org/  :  Melbourne, VIC

      reply	other threads:[~2010-11-02  0:43 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-31 15:55 btrfs-convert fails Helmut Hullen
2010-10-31 19:26 ` Helmut Hullen
2010-11-01  2:06 ` Yan, Zheng 
2010-11-01  8:02   ` Helmut Hullen
2010-11-01  9:49     ` Felix Blanke
2010-11-01 11:55       ` Helmut Hullen
2010-11-01 12:20         ` cwillu
2010-11-02  0:43           ` Chris Samuel [this message]

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