🚀 go-pugleaf

In article <nodq9mk@zuni.esd.sgi.com> olson@anchor.esd.sgi.com (Dave Olson) writes:
>In <AJC.92Jul24120000@thendara.pa.dec.com> ajc@pa.dec.com (AJ Casamento) writes:
>|   My understanding of the SCSI-2 standard is that it calls out a standard
>| minimum delay of 200MHz (5 Mtransfers/sec). It also allows for the implementa-
>| tion of Fast Differential (I believe that Fast Single-ended is not supported
>| and would only allow a cable length of 0.5M) which calls out a minimum delay
>| of 100MHz (10 Mtransfers/sec).
>
>There is an implementors note that fast SCSI might require differential
>to be reliable.  This hasn't turned out to be the case (actual experience).
>Several drive vendors are saying that they support single ended fast SCSI,
>but are also saying that they want the bus to be 4 meters or less, in
>this case, rather than 6 m.

Hmm.  I've regularly had problems with single-ended SCSI-1 over 2m on one (Sun)
system, and other people who've had problems (eg crashes during heavy paging
activity, which is when we had most problems too) have had the problems go away
when they've changed to shorter cables.  I'd be cautious about using the full
6m, and spent a bit of time getting data on it from the SCSI committee people.
(I'm working on a project where physical constraints use of the whole 6m.)

The info isn't on line OR simple, so don't plague me with requests unless
you've a specific question!  B^>

Damon
-- 
Damon Hart-Davis | Tel/Fax: +44 81 755 0077 |1.21|| ALL MAIL FREE.
Internet: dhd@exnet.co.uk | Also: Damon@ed.ac.uk || Hotrod motor groups soon.
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