Date: Tue, 1 Jul 1997 20:20:22 -0700 (PDT) From: dan@math.berkeley.edu (Dan Strick) To: freebsd-scsi@FreeBSD.ORG Cc: dan@math.berkeley.edu, jdn@qiv.com Subject: Re: 2.2.2-RELEASE/Viper anomolies Message-ID: <199707020320.UAA04700@math.berkeley.edu>
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> Should all devices be parity enabled? -- or none? All devices should be parity enabled. In most cases, they always generate SCSI bus parity and the "parity enable" option just causes them to check it. You should always try to check the configuration of every SCSI device that you install on a system. Vendors are particularly indifferent about enabling parity checking because they would rather that the end user lose an occasional bit than complain about mysterious error messages from his SCSI system. Not all models of sun checked SCSI bus parity under all releases of SunOS, probably to accommodate old sun SCSI peripherals which were still being sold with SS1s at the time the SS1s were first introduced. It might be that your SCSI tape drive has always generated bad SCSI parity and your SS1+ didn't care, though I think this less likely than some new problem (e.g. an excessively long SCSI bus operating at a faster speed), or perhaps the tape drive has problems with synchronous SCSI bus transfers (something else that SS1s and SS1+s didn't do by default on their motherboard SCSI bus). > Would putting it on a controller by itself be a benifit? I often do this with devices (such as a QIC tape drive) that are likely to hog the SCSI bus because the manufacturer doesn't want to spend more money on the SCSI interface than is necessary to make *his* device run at its full speed. I also like to keep my SCSI busses short and splitting them up helps a lot. Dan Strick dan@math.berkeley.edu
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