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From: Dan Ts'o <dan@dnn.rockefeller.edu>
Subject: Re: Bizarre SCSI problem (3 disks work, 4 don't) (2940UW/Quantum Atlas II)
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Date: Sun, 9 Feb 1997 03:43:51 GMT
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In comp.unix.bsd.freebsd.misc Eric Ratermann <ericrat@erinet.com> wrote:
: Man I'm glad to hear I'm not alone on this one, I had the same problem
: with 4 4.5 gig FW Quantums (don't remember model) in a Ibm Server 320
: with the 2940 UW. A $60.00 forced perfect terminator and a lot of
: dinking (that's a very high tech term for using Fuck I don't know try
: anything) made it work. Besides, after spending $18,000 dollars on a
: server I figured sixty to ease my termination worries didn't matter.
: ANYWAY
: What also worked was to enable termination on EVERY drive. It is the one
: of mare uncouth things I've seen done to a PC but it worked. I can dream
: up a few strange reasons about why but it simply don't make sense. (Any
: Ideas???). The system benchmarked fine afterwards, and the customer has
: a 8 or 10 in service.
Probably just dampening reflections.
I've never seen this discussed in relation to SCSI but I remember
from Unibus days that it was common practice to vary the cable length between
nodes with non-integral lengths to avoid reinforcement of reflections.
Certainly by removing one of 4 disks off the bus would do that.
--
Cheers,
Dan Ts'o 212-327-7671
Dept. of Neurobiology FAX: 212-327-7671
The Rockefeller University
1230 York Ave. Box 138 dantso@cris.com
New York, NY 10021 dan@dna.rockefeller.edu