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Message-ID: <19980719220905.C25078@mi.uni-koeln.de>
Date: Sun, 19 Jul 1998 22:09:05 +0200
From: Stefan Esser <se@FreeBSD.ORG>
To: "Saad M. Waraich" <Saad.Waraich@Pakistan.NCR.COM>, stable@FreeBSD.ORG
Cc: leo@talcom.net, Stefan Esser <se@FreeBSD.ORG>
Subject: Re: NCR 875 and tagged queing. Broken?
References: <19980712103316.07090@mi.uni-koeln.de> <199807130844.NAA11954@isb.ncr.com.pk>
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In-Reply-To: <199807130844.NAA11954@isb.ncr.com.pk>; from Saad M. Waraich on Mon, Jul 13, 1998 at 01:44:54PM +0500
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On 1998-07-13 13:44 +0500, "Saad M. Waraich" <Saad.Waraich@Pakistan.NCR.COM> wrote:
> The problem is a combination of the NCR driver and the Atlas III drive.
> I have an 875 based card (Tekram 390F) and a 2 gig. Atlas III drive and 
> I've seen this problem a lot.

It is specific to certain drives.

> Upgrading the drive's firmware didn't help either. Is it worth it to talk
> to Quantum about this problem ? They could easily shrug it off saying 
> that it is a problem in the driver.

Well, it is in fact a problem of the driver
if it does not survive a QUEUE_FULL status.

If your system runs reliable even though 
there are those messages "assertion failed"
logged, then just wait for the CAM driver to
be released. You may try the pre-release 
version of the CAM driver, but it is not as
well tested as that for the Adaptec cards,
and I'm not sure how robust it is on a 
highly loaded server.

You may compare performance with tags enabled
and without, and it depends on your work load,
whether there will be that much of a difference.

I have used "Bonnie" (in ports/benchmarks) to 
estimate the impact of running without tags.
But that might not at all be a realistic test
for the kind of load your system sees.

Regards, STefan



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