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Date: Tue, 5 Jul 2005 14:10:57 -0400
From: Sonny Rao <sonny@burdell.org>
To: Al Boldi <a1426z@gawab.com>
Cc: "'Jens Axboe'" <axboe@suse.de>, "'David Masover'" <ninja@slaphack.com>,
       "'Chris Wedgwood'" <cw@f00f.org>, "'Nathan Scott'" <nathans@sgi.com>,
       linux-xfs@oss.sgi.com, linux-kernel@vger.kernel.org,
       linux-fsdevel@vger.kernel.org, reiserfs-list@namesys.com
Subject: Re: XFS corruption during power-blackout
Message-ID: <20050705181057.GA16422@kevlar.burdell.org>
Mail-Followup-To: Sonny Rao <sonny@burdell.org>,
	Al Boldi <a1426z@gawab.com>, 'Jens Axboe' <axboe@suse.de>,
	'David Masover' <ninja@slaphack.com>,
	'Chris Wedgwood' <cw@f00f.org>, 'Nathan Scott' <nathans@sgi.com>,
	linux-xfs@oss.sgi.com, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, reiserfs-list@namesys.com
References: <20050705154919.GA13262@kevlar.burdell.org> <200507051725.UAA07417@raad.intranet>
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On Tue, Jul 05, 2005 at 08:25:11PM +0300, Al Boldi wrote:
> Sonny Rao wrote: {
> > > >On Wed, Jun 29, 2005 at 07:53:09AM +0300, Al Boldi wrote:
> > > >>What I found were 4 things in the dest dir:
> > > >>1. Missing Dirs,Files. That's OK.
> > > >>2. Files of size 0. That's acceptable.
> > > >>3. Corrupted Files. That's unacceptable.
> > > >>4. Corrupted Files with original fingerprint. That's ABSOLUTELY 
> > > >>unacceptable.
> > > >
> > 2. Moral of the story is: What's ext3 doing the others aren't?
> 
> Ext3 has stronger guaranties than basic filesystem consistency.
> I.e. in ordered mode, file data is always written before metadata, so the
> worst that could happen is a growing file's new data is written but the
> metadata isn't updated before a power failure... so the new writes wouldn't
> be seen afterwards.
> 
> }
> 
> Sonny,
> Thanks for you input!
> Is there an option in XFS,ReiserFS,JFS to enable ordered mode?

I beleive in newer 2.6 kernels that Reiser has ordered mode (IIRC, courtesy
of Chris Mason), but XFS and JFS do not support it.  I seem to remember
Shaggy (JFS maintainer) saying in older 2.4 kernels he tried to write
file data before metadata but had to change that behavior in 2.6, not
really sure why or anything beyond that.
 
Sonny