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Date:      Fri, 14 Aug 1998 12:46:31 -0600 (MDT)
From:      "Justin T. Gibbs" <gibbs@narnia.plutotech.com>
To:        Matti Aarnio <matti.aarnio@sonera.fi>
Cc:        aic7xxx@FreeBSD.ORG
Subject:   Re: AHA2790UW has speed-limit problems ?
Message-ID:  <199808141846.MAA03259@narnia.plutotech.com>
In-Reply-To: <19980814141956Z92206-32591%2B1@mea.tmt.tele.fi>

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>   Four Ultra-Wide (SingleEnded) disks on high quality cable inside
> DEC PWS 433a workstation chassis attached to AHA2940UW host adapter.

How long is this cable.  How far apart are the connectors in the chain.
Have you tried using a "forced perfect" terminator?

> The Kludge-Cure:
> 
>   Lower the speed of the device in the adapter bios configuration
> utility.  In fact lower them all, and no SCSI-timeout problems appear.

This would indicate bus signal quatlity problems at high speeds.

> Question:
> 
>   Is there ANYTHING that is possible to do to in this type of environment
> so that I could (reliably) run faster disk-transfer speeds ?

Shorten the cables.  Ensure that the distance between all connectors on
the cable are equal.  Use a forced perfect terminator.

--
Justin

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