Message-ID: <45C0E204.3030901@rtr.ca>
Date: Wed, 31 Jan 2007 13:37:56 -0500
From: Mark Lord <liml@rtr.ca>
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To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Alan <alan@lxorguk.ukuu.org.uk>, Ric Wheeler <ric@emc.com>,
       "Eric D. Mudama" <edmudama@gmail.com>, linux-kernel@vger.kernel.org,
       IDE/ATA development list <linux-ide@vger.kernel.org>,
       linux-scsi <linux-scsi@vger.kernel.org>, dougg@torque.net
Subject: Re: [PATCH] scsi_lib.c: continue after MEDIUM_ERROR
References: <200701301947.08478.liml@rtr.ca>	 <1170206199.10890.13.camel@mulgrave.il.steeleye.com>	 <311601c90701301725n53d25a74g652b7ca3bfc64c56@mail.gmail.com>	 <45BFF3D6.9050605@rtr.ca>	<45C00AEE.1090708@emc.com>	 <45C0B0DC.8030501@rtr.ca> <20070131152301.19a8a5ac@localhost.localdomain>	 <45C0D8A1.2030506@rtr.ca> <1170267198.3402.58.camel@mulgrave.il.steeleye.com>
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James Bottomley wrote:
> On Wed, 2007-01-31 at 12:57 -0500, Mark Lord wrote:
>> Alan wrote:
>>>> When libata reports a MEDIUM_ERROR to us, we *know* it's non-recoverable,
>>>> as the drive itself has already done internal retries (libata uses the
>>>> "with retry" ATA opcodes for this).
>>> This depends on the firmware. Some of the "raid firmware" drives don't
>>> appear to do retries in firmware.
>> One way to tell if this is true, is simply to time how long
>> the failed operation takes.  If the drive truly does not do retries,
>> then the media error should be reported more or less instantly
>> (assuming drive was already spun up).
> 
> Well, the simpler way (and one we have a hope of implementing) is to
> examine the ASC/ASCQ codes to see if the error is genuinely unretryable.

My suggestion above was not for a kernel fix,
but rather just as a way of determining if drives
which claim "no retries" actually do them or not.  :)

> I seem to have dropped the ball on this one in that the scsi_error.c
> pieces of this patch
> 
> http://marc.theaimsgroup.com/?l=linux-scsi&m=116485834119885
> 
> I thought I'd applied.  Apparently I didn't, so I'll go back and put
> them in.

Good.  That would be a useful supplement to the patch I posted here.

Cheers
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