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To: Jens Axboe <axboe@suse.de>
Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: [PATCH] 2.4.x write barriers (updated for ext3)
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From: Peter Osterlund <petero2@telia.com>
Date: 13 Mar 2002 23:37:24 +0100
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Jens Axboe <axboe@suse.de> writes:

> On Mon, Mar 11 2002, Kurt Garloff wrote:
> > disks (DASDs), Write-Once and Optical Memory devices. (Funny enough, the
> > SCSI spec also lists SYNCHRONIZE_CACHE for CD-Rom devices
> 
> Hey, I use SYNCHRONIZE_CACHE in the packet writing stuff for CD-ROM's
> all the time :-). Not all are read-only. In fact, Peter Osterlund
> discovered that if you have pending writes on the CD-ROM it's a really
> good idea to sync the cache prior to starting reads or they have a nasty
> tendency to time out.

Not only time out, some drives give up immediately with SK/ASC/ASCQ
05/2c/00 "command sequence error" unless you flush the cache first.
After some googling, I found a plausible explanation for that
behaviour here:

http://www.rahul.net/endl/cdaccess/t10/email/mmc/1997/m9703031.txt

-- 
Peter Osterlund - petero2@telia.com
http://w1.894.telia.com/~u89404340
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