Date: Sun, 4 Jan 2009 04:23:49 -0500
From: Christoph Hellwig <hch@infradead.org>
To: Adam Nielsen <a.nielsen@shikadi.net>
Cc: Christoph Hellwig <hch@infradead.org>,
       LKML Mailinglist <linux-kernel@vger.kernel.org>
Subject: Re: XFS internal error xfs_da_do_buf(1) at line 2015 of file
	fs/xfs/xfs_da_btree.c
Message-ID: <20090104092349.GA26194@infradead.org>
References: <49600DE6.2080108@shikadi.net> <20090104074659.GA16775@infradead.org> <49607B5B.3070707@shikadi.net>
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On Sun, Jan 04, 2009 at 07:03:23PM +1000, Adam Nielsen wrote:
> No, I didn't realise I had to do that...in fact I didn't even realise 
> SATA disks *had* write caches, I thought the cache was for reading 
> only...

Which would be the better default (it's what high-end disks generally
do by default).  I've been wondering for a while how we can make default
setups in the presence of lvm/dm more secure, but there hasn't been
any progress yet.

>> Run xfs_repair over it to fix up the directory, and make sure to
>> configure your disks properly so that it doesn't happen again..
>
> Will do, thanks for the advice!  Is there any standard way to disable 
> write caching on a SATA disk?  hdparm -W seems to do the trick, but then 
> I can't run that until the system is up and running, leaving a small 
> window of opportunity for something to go wrong.

On Debian based systems you can add -W0 to /etc/default/hdparm and
it gets executed before the root filesystem is remounted read-write,
I'm not sure how other distributions handle it.

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