From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Brown <git@davidb.org>
Subject: Re: git repo being corrupted?
Date: Mon, 7 Apr 2008 09:15:25 -0700
Message-ID: <20080407161525.GA25894@old.davidb.org>
References: <47F9F1A1.30009@diamand.org> <20080407111740.GA12776@bit.office.eurotux.com> <47FA03C4.9030104@diamand.org> <20080407113921.GA13667@bit.office.eurotux.com>
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Cc: Luke Diamand <luke@diamand.org>, git@vger.kernel.org
To: Luciano Rocha <luciano@lsd.di.uminho.pt>
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On Mon, Apr 07, 2008 at 12:39:21PM +0100, Luciano Rocha wrote:

>> > You're using XFS. Did you have a power fail in the recent past?
>> 
>> How did you know?
>
>XFS doesn't order metadata writes with data writes, so if the power
>fails, it can find an update in the journal but the data wasn't written.
>Then it fills the file with zeroes to the new size.

This behavior should be a lot better for recent kernels.

xfs does even better with write barriers.  But any file change that is more
than one write can be corrupted or split by an inopportune powerdown.

David