From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andries Brouwer Subject: Re: aic7xxx sets CDR offline, how to reset? Date: Wed, 4 Sep 2002 12:37:37 +0200 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20020904103737.GA9936@win.tue.nl> References: <20020903171321.A12201@redhat.com> <200209032148.g83LmeP09177@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <200209032148.g83LmeP09177@localhost.localdomain> List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: "Justin T. Gibbs" , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org On Tue, Sep 03, 2002 at 04:48:39PM -0500, James Bottomley wrote: > If you're hitting error recovery so often that whether it recovers > in half a second or several seconds makes a difference, I'd say > there's something else wrong. Not that I want to contradict, but an example. Without my sd.c patch from yesterday or so (fixing MODE SENSE calls) an "insmod usb-storage.o" would take 14 minutes and 6 seconds for me. [One USB device, with 3 subdevices, gets into a bad state when presented with a MODE SENSE command that asks for more than the 56 bytes it has available. For each of the three subdevices we get a long sequence of retries, abort, reset, host reset, bus reset before it is taken off-line.] The scsi error recovery has many bad properties, but one is its slowness. Once it gets triggered on a machine with SCSI disks it is common to have a dead system for several minutes. I have not yet met a situation in which rebooting was not preferable above scsi error recovery, especially since the attempt to recover often fails. Andries