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Date: Wed, 1 Apr 2009 17:50:40 -0400
From: Theodore Tso <tytso@mit.edu>
To: Chris Mason <chris.mason@oracle.com>
Cc: "Andreas T.Auer" <andreas.t.auer_lkml_73537@ursus.ath.cx>,
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Subject: Re: Linux 2.6.29
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On Wed, Apr 01, 2009 at 12:02:26PM -0400, Chris Mason wrote:
> 
> If we crash during the rsync, the backup logs will yell.  If we crash
> just after the rsync, the backup logs won't know.  The data could still
> be gone.

So have rsync call the sync() system call before it exits.  Not a big
deal, and not all that costly.  So basically what I would suggest
doing for people who are really worried about rsync performance with
flush-on-rename is to create a patch to rsync which creates a new
flag, --unlink-before-rename, which will defeat the flush-on-rename
hueristic; and if this patch also causes rsync to call sync() when it
is done, it should be quite safe.

						- Ted
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