Date: Fri, 14 Aug 1998 23:58:26 +0300 (EEST) From: Matti Aarnio <matti.aarnio@sonera.fi> To: gibbs@narnia.plutotech.com (Justin T. Gibbs) Cc: matti.aarnio@sonera.fi, aic7xxx@FreeBSD.ORG Subject: Re: AHA2790UW has speed-limit problems ? Message-ID: <19980814205828Z92206-1428%2B89@mea.tmt.tele.fi> In-Reply-To: <199808141846.MAA03259@narnia.plutotech.com> from "Justin T. Gibbs" at "Aug 14, 98 12:46:31 pm"
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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? That is the original Digital supplied hardware, and so far I have not questioned their quality.. The cable assembly is made by Amphenol into DECs specification to be used in this machine. > > 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. Indeed. Or perhaps the installation of additional disks was not done by a qualified field engineer, and the cable routing/ twisting inside the chassis is suboptimal -- this is very likely, as I am not a qualified field engineer for DEC hardware... > > 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. Yeah, maybe next time when I open the box I will investigate these issues. Right now it is stable, and I have code to write, and code to compile... > -- > Justin /Matti Aarnio <matti.aarnio@sonera.fi> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe aic7xxx" in the body of the message
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