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Date:      Mon, 28 Jul 1997 19:53:40 +0200
From:      Stefan Esser <se@FreeBSD.ORG>
To:        Michael Beckmann <petzi@apfel.de>
Cc:        scsi@FreeBSD.ORG, Stefan Esser <se@FreeBSD.ORG>
Subject:   Re: Tagged Command Queuing on ncr
Message-ID:  <19970728195340.09850@mi.uni-koeln.de>
In-Reply-To: <Pine.BSF.3.95.970727141616.372A-100000@bsd.fs.bauing.th-darmstadt.de>; from Michael Beckmann on Sun, Jul 27, 1997 at 02:25:05PM %2B0200
References:  <Pine.BSF.3.95.970727141616.372A-100000@bsd.fs.bauing.th-darmstadt.de>

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On Jul 27, Michael Beckmann <petzi@apfel.de> wrote:
> Hello,
> 
> how do I turn off tagged command queuing on the ncr driver ? I have two

Which version of FreeBSD are you using ?

> disks that don't seem to like it. I do not want to turn it off on the
> entire system, which also has an ahc driven controller in it, with
> tagged command queuing turned on via AHC_TAGENABLE. Can SCSI_NCR_DFLT_TAGS
> do this ?

You can turn off tags for single drives.
This is done differently under 2.x and 
-current. Look at the example for the HP
C3274 and C3275 in /sys/scsi/scsiconf.c 
in -current, if you use that:

	{
		T_DIRECT, T_DIRECT, T_FIXED, "HP", "C372*", "*",
		"sd", SC_ONE_LU, SD_Q_NO_TAGS
	},

In 2.x look for a line reading:

		ncr_setmaxtags (tp, SCSI_NCR_DFLT_TAGS);

and change the second parameter to 0.
You can then set the number of tags from
a startup file for all drives that support
tagged commands. Assuming that target 1 
and 2 don't support tags, but the rest of
your targets does, you want to execute the
following command:

# ncrcontrol -t0 -t3 -t4 -t5 -t6 -s tags=4

for the default of 4 tags per drive. (This 
assumes disk drives on all targets, and 7
as the host adapter ID.)

Regards, STefan



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