Date: Fri, 28 Nov 1997 13:08:47 -0700 (MST) From: gibbs@narnia.plutotech.com (Justin T. Gibbs) To: Bill Vermillion <bill@bilver.oau.org> Cc: isp@FreeBSD.org Subject: Re: Adaptec 2940 and FreeBSD 2.2.2-RELEASE Message-ID: <199711282008.NAA11788@narnia.plutotech.com> In-Reply-To: <199711281446.JAA28643@bilver.magicnet.net> References: <199711281446.JAA28643@bilver.magicnet.net>
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In article <199711281446.JAA28643@bilver.magicnet.net>, Bill Vermillion <bill@bilver.oau.org> writes: > > When I need the multiples busses like the 3940 - I'd go with the > DPT. But I've never anything but BL in the 3 or 4 FreeBSD boxes > I've used. The problem with using Buslogic cards is not the hardware, but the driver support. So long as our Buslogic driver does not support tagged command queuing, the Buslogic cards will never perform as well as the Adaptec or Symbios cards. > Good cables are a must. However .5m cables (if you have multiple > targets) is definately not SCSI spec, which is .3m between targets > and .1m stub. People missunderstand the SCSI spec all of the time. In part this is because this section is poorly written. The main thing to come out of the stub/device spacing requirement is the minimum 3 to 1 ratio. For internal cabling configurations, your stub length is determined by the PCB tracings on the drive's electronic board which is typically less than .05m. This means you can actually cluster devices fairly close together. Even more important than device spacing length is spacing consistency, having devices and cables with similar loads, termination, and overall cable length. -- Justin T. Gibbs =========================================== FreeBSD - Turning PCs into workstations ===========================================
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