Subject: Re: Crashed Drive, libata wedges when trying to recover data
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Brad Campbell <brad@wasp.net.au>
Cc: Greg Stark <gsstark@mit.edu>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Jeff Garzik <jgarzik@pobox.com>
In-Reply-To: <413868CE.7070303@wasp.net.au>
References: <87oekpvzot.fsf@stark.xeocode.com>
	 <4136E277.6000408@wasp.net.au> <87u0ugt0ml.fsf@stark.xeocode.com>
	 <413868CE.7070303@wasp.net.au>
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Date: Fri, 03 Sep 2004 15:09:58 +0100
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On Gwe, 2004-09-03 at 13:51, Brad Campbell wrote:
> Yep.. About 30 seconds per sector is the timeout whereas with 2.6.6 it would never do anything after 
> the first timeout. Yes it's slow, yes it could probably be sped up but it is certainly indicative of 
> a dodgy disk.
> 
> Use something like http://www.kalysto.org/utilities/dd_rhelp/index.en.html and you might have better 
> results.
> 
> Jeff, do we really have to wait 30 seconds for a timeout? If the drive hits an unreadble spot I 
> would have thought it would come back to us with a read error rather than timing out the command.

The drive will retry for a few seconds then fail. The failure now
generates a SCSI medium error to the core scsi layer and it does like to
issue a few retries. The default retry count for scsi is probably too
high for SATA given the drive retries.

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