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Newsgroups: comp.unix.bsd Path: sserve!manuel.anu.edu.au!munnari.oz.au!spool.mu.edu!uwm.edu!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!usc!cs.utexas.edu!sun-barr!ames!kronos.arc.nasa.gov!iscnvx!netcomsv!netcom.com!alm From: alm@netcom.com (Andrew Moore) Subject: Re: Weird Problem (50 MHz, SCSI) Message-ID: <1992Oct23.042521.22001@netcom.com> Keywords: SCSI, file corruption Organization: Netcom - Online Communication Services (408 241-9760 guest) References: <1992Oct14.220847.22548@sics.se> <168382@mbf.UUCP> Date: Fri, 23 Oct 1992 04:25:21 GMT Lines: 39 In article <168382@mbf.UUCP> fmt@mbf.UUCP (Mike Trimberger) writes: >In article <1992Oct14.220847.22548@sics.se> jonas@sisu.se (Jonas Lagerblad) writes: >>I have had quite a lot of problems with two different 50 Mhz cards, I have >>traced the problem to the cache memory, which I don't think behaves quite > ... >>I posted an article to this newsgroup a week ago inquiring if anyone >>besides me have had problems with their 50MHz boards and I have got approx. >>10 answers where most people have had some strange memory problems, most >>of them had a SCSI controller. > ... >>My problems have disappeared totally since disabling the cache, but I have >>ordered new faster cache memory, and is eagerly waiting for it to arrive. > >We have been evaluating some 50MHz Intel PC systems here and discovered >that the caches don't work. We looked further and discovered that they >were shipped direct from the manufacturer to us with external cache chips >which were too slow to keep up with the 50MH '486. When we went looking >for chips that are fast enough, there were none on the market! Actually >there are a very few but the IC manufacturers are still sampling the new >parts. We were able to get some by having an IC distributer cherry-pick >parts that were labeled slower. > >The parts that did NOT work were 12ns rams. We had to use 10ns cache >rams. Only 1 source so far is Toshiba. > >>So my advice is to try to disable the cache, and see what happens. > >Good advice! If you have problems with a 50MHz '486, disable the >external cache and see if it will work correctly. With the extra >demands that a UNIX system puts on the system, the problems show >up. The reason that our manufacturer never saw a problem, was that >they test the system using MS-DOG and Netware. For what it's worth, I am able to run ESIX VR4 on a SCSI disk with cache enabled on a motherboard which has problems under 386BSD. The implication is that 386BSD is at least an accessory to the problem. Either replacing the SCSI controller with IDE or disabling cache solves the problem. -Andrew Moore <alm@netcom.com>