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Newsgroups: comp.os.386bsd.questions Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!netnews.upenn.edu!news.cc.swarthmore.edu!psuvax1!news.pop.psu.edu!news.cac.psu.edu!howland.reston.ans.net!europa.eng.gtefsd.com!MathWorks.Com!zombie.ncsc.mil!paladin.american.edu!constellation!rex!ben From: ben@rex.uokhsc.edu (Benjamin Z. Goldsteen) Subject: Re: SCSI controller recomendations requested Message-ID: <Cw6rsI.C4r@rex.uokhsc.edu> Date: Thu, 15 Sep 1994 19:36:17 GMT Reply-To: benjamin-goldsteen@uokhsc.edu References: <Cw3nuw.E8@galaxia.network23.com> <356jdu$irb@agate.berkeley.edu> <MICHAELV.94Sep14135401@MindBender.HeadCandy.com> Organization: Health Sciences Center, University of Oklahoma Lines: 62 michaelv@MindBender.HeadCandy.com (Michael L. VanLoon) writes: >In article <356jdu$irb@agate.berkeley.edu> jkh@violet.berkeley.edu (Jordan K. Hubbard) writes: > The Bt445S seems to come in a variety of confusing revisions, some > broken some not, thus the "luck" factor. I have one that works beautifully, > and other folks have had the worst luck. Buslogic basically really screwed > the pooch on their VLB card and the road is litered with their previous > failure attempts. Avoid picking one of these failed attempts up and you're > fine, otherwise.. It's always hard to know what a dealer has in stock and > how old it is. >Not to disagree with your findings, but I've also been told this has >as much to do with the motherboard as with the SCSI card. I've had >people tell me they're using bt445s cards that aren't supposed to work >right, but do, on their motherboards with no problems. Other people >have had problems even with the "corrected" SCSI boards, when used in >flaky motherboards. >VLB is a very loosely defined "standard". It leaves a lot of >implementation decisions up to the person designing the motherboard. >Hence, you will not get consistent results across all VLB >motherboards. > The other two give commendable stability and performance. >I'd have to disagree here. I've watched with my own eyes a >demonstration of just how slow the 1542 boards are. This was with >Windoze NT, but it still applies. We have several Dell Pentium boxes >at a place where I work (one of my many jobs), that run Windoze NT. >My machine is a 66MHz Pentium, and has a NCR 53c810 SCSI controller in >it. We recently acquired a Dell XPS 90 (90MHz Pentium) machine, that >came supplied with an Adaptec 1542. Both machines have 32MB of RAM, >512k cache, and newish 1GB SCSI drives. >We decided to see how fast the two machines booted, mainly to see just >how fast the 90MHz Pentium would be. We got some surprising results. >We set them beside each other, got to the OS boot menu, and hit return >for Windoze NT at the same time on both machines. The XPS 90 screamed >thru the self tests, and went right into the disk check screen while >the 66 was still sitting checking memory. The 66 got to the disk >checking screen while the 90 was about half way thru. Then all hell >broke loose. The 66 with the PCI SCSI checked thru the disks and was >booting the OS before the 90 even finished checking disks. The 66 was >at the login banner as the 90 was just starting up the OS. The >difference in disk speed was simply astounding, and couldn't be made >any clearer visually. >While this doesn't apply directly to the a 486 running a VLB card, >believe me, buying an ISA-bus SCSI controller for a modern-day >computer is definitely going to make the SCSI controller your main >bottleneck for throughput. How can the ISA-bus be a bottleneck for disk drives that can't even push what the ISA-bus can sustain (ISA-bus maxes at 4-5MB/sec). While we are on this subject, can somebody tell me why an IBM RS/6000-950 can read a SCSI-2 disk at 3500KB/s on a SCSI-2 bus but only gets 2500KB/s on a SCSI-1 bus (from the same SCSI-2 drive)? I thought the sustained rate on SCSI-1 was 5MB/sec. -- Benjamin Z. Goldsteen