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Date:      Fri, 3 Sep 1999 16:15:49 -0600 (MDT)
From:      "Kenneth D. Merry" <ken@kdm.org>
To:        davids@webmaster.com (David Schwartz)
Cc:        freebsd-scsi@FreeBSD.ORG
Subject:   Re: Probably ahc hardware problem.
Message-ID:  <199909032215.QAA17118@panzer.kdm.org>
In-Reply-To: <000001bef658$695f97e0$021d85d1@youwant.to> from David Schwartz at "Sep 3, 1999 03:05:19 pm"

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[ CCing my reply to the -scsi list, I hope you don't mind, but I think other
folks might be interested in this ]

David Schwartz wrote...
> 
> da0 at ahc0 bus 0 target 0 lun 0
> da0: <CONNER CFP4207S  4.28GB 1524> Fixed Direct Access SCSI-2 device
> da0: 10.000MB/s transfers (10.000MHz, offset 15), Tagged Queueing Enabled
> da0: 4096MB (8388608 512 byte sectors: 255H 63S/T 522C)
> 
> 	It's also known as the ST14207N.
> 
> 	Do you think I need a firmware upgrade? Maybe it's a heat problem? Or power
> supply stability causing the drive to zonk out?

I've seen other Conner drives that have problems doing tagged queueing. 
(The Conner CFP 2107 is quirked in the transport layer.)  A firmware lockup
is possible if they don't handle tagged queueing properly.

Here's a quick way to figure out whether that's the problem:

camcontrol negotiate da0 -T disable -v -a

That should disable tagged queueing for that drive.  Then try pounding the
drive again, and see if the problem returns.  If not, you can then try
re-enabling tagged queueing (by changing the 'disable' in the above command
to 'enable') and using the 'camcontrol tags' command to adjust the number
of tags allowed for that device.

Some drives only reliably handle a few concurrent transactions, and some
don't handle tagged queueing well at all.  It may be that your drive will
handle only a few, and you may be able to determine what the maximum number
is through experimentation.  It also may be that tagged queueing doesn't
work well at all for that drive, and so should be disabled.

In any case, try the above experiment and see what happens.

Ken
-- 
Kenneth Merry
ken@kdm.org


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