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Date:      Thu, 10 Feb 2000 04:55:43 -0500
From:      Chris Johnson <cjohnson@palomine.net>
To:        "Justin T. Gibbs" <gibbs@narnia.plutotech.com>
Cc:        scsi@FreeBSD.org, lamaster@nren.nasa.gov
Subject:   Re: BT-948 timeouts
Message-ID:  <20000210045543.A57016@palomine.net>
In-Reply-To: <200002071435.HAA43271@narnia.plutotech.com>; from gibbs@narnia.plutotech.com on Mon, Feb 07, 2000 at 07:35:22AM -0700
References:  <20000206141744.A2557@palomine.net> <200002071435.HAA43271@narnia.plutotech.com>

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On Mon, Feb 07, 2000 at 07:35:22AM -0700, Justin T. Gibbs wrote:
> > da0 at bt0 bus 0 target 6 lun 0
> > da0: <QUANTUM FIREBALL SE4.3S PJ0A> Fixed Direct Access SCSI-2 device
> > da0: 10.000MB/s transfers (10.000MHz, offset 15), Tagged Queueing Enabled
> > da0: 4110MB (8418816 512 byte sectors: 255H 63S/T 524C)
> 
> The buslogic cards don't give any indication of the "queue full" condition.
> This means that CAM cannot know when to reduce the number of commands
> sent to a device if it can only handle a few.  My guess is that the
> buslogic firmware is not gracefully dealing with the queue full
> condition so we see timeouts.  My hunch is that if you forced the
> number of concurrent transactions down to 8 (what I recall is the
> limit for this drive), then your timeouts will cease.  You can
> do this with the "camcontrol tags" command.

Thanks very much for your response.

Here's what I did:

su-2.03# camcontrol tags da0 -N 8

And here's the result:

su-2.03# camcontrol tags da0 -v
(pass0:bt0:0:6:0): dev_openings  8
(pass0:bt0:0:6:0): dev_active    0
(pass0:bt0:0:6:0): devq_openings 8
(pass0:bt0:0:6:0): devq_queued   0
(pass0:bt0:0:6:0): held          0
(pass0:bt0:0:6:0): mintags       2
(pass0:bt0:0:6:0): maxtags       255

This seems to have done the trick. I built a world without any timeouts, which
I hadn't been able to do before I made the change.

Is there a fancy way to make this change survive across boots, or should I just
shove the camcontrol command in a script that runs at boot time?

How would I go about learning what the tags setting should be for a particular
drive? 

Chris


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