From: Eric Sandeen <sandeen@sandeen.net>
To: Russell Cattelan <cattelan@thebarn.com>
Cc: Martin Steigerwald <Martin@Lichtvoll.de>,
Chris Wedgwood <cw@f00f.org>,
xfs@oss.sgi.com
Subject: Re: massively truncated files with XFS with sudden power loss on 2.6.27 and 2.6.28
Date: Mon, 29 Dec 2008 15:56:45 -0600 [thread overview]
Message-ID: <4959479D.8010801@sandeen.net> (raw)
In-Reply-To: <49592E7D.4050208@xfs.org>
Russell Cattelan wrote:
> Chris Wedgwood wrote:
>> this will bite xfs more than ext3 w/ ordered mode
>>
> Delayed allocation is a factor (and this will be true of any fs
> supporting delayed allocation)
> holding of data flushes helps reduce fragmentation by allowing larger
> segments to be flushed out,
> but it increases the time data is held in cache and thus create a larger
> window for data loss.
That's not quite accurate AFAIK; yes, xfs has delayed allocation, but it
pushes data to disk on the same schedule (by default) as any other
filesystem; when pdflush goes off (30s) or under memory pressure.
The only difference is that xfs (or any delalloc fs) allocates at flush
time not at write time.
But this does not imply that xfs is holding off flushes for longer due
to delayed allocation; I don't want it to sound like xfs is putting data
integrity at risk due to delalloc, because it's not ...
-Eric
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next prev parent reply other threads:[~2008-12-29 21:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-29 18:20 massively truncated files with XFS with sudden power loss on 2.6.27 and 2.6.28 Martin Steigerwald
2008-12-29 19:03 ` Chris Wedgwood
2008-12-29 19:08 ` Eric Sandeen
2008-12-29 20:00 ` Martin Steigerwald
2008-12-30 0:14 ` Chris Wedgwood
2008-12-29 19:09 ` Russell Cattelan
2008-12-29 19:20 ` Christoph Hellwig
2008-12-29 19:29 ` Chris Wedgwood
2008-12-29 20:09 ` Russell Cattelan
2008-12-29 20:17 ` Chris Wedgwood
2008-12-29 21:25 ` Russell Cattelan
2008-12-29 21:56 ` Eric Sandeen [this message]
2008-12-29 19:48 ` safe writing in applications (was: Re: massively truncated files with XFS with sudden power loss on 2.6.27 and 2.6.28) Martin Steigerwald
2008-12-29 19:54 ` Christoph Hellwig
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