From: olson@anchor.esd.sgi.com (Dave Olson)
Newsgroups: comp.sys.sgi
Subject: Re: Hard drives...
Date: 30 Dec 92 07:53:11 GMT
Organization: Silicon Graphics, Inc.  Mountain View, CA

In <72606@cup.portal.com> thad@cup.portal.com (Thad P Floryan) writes:

| In article <1hr2viINNq25@calvin.NYU.EDU>
| roy@mchip00.med.nyu.edu (Roy Smith) writes:
| 
| | [...]
| | 	As far as I'm concerned, SCSI means Some Crappy Stupid Interface.  I
| | guess it beats SMD, but it sure doesn't live up the the wonderful promises
| | it made (not to mention the random connector confusion; I know of 3 commonly
| | used connectors, and I havn't even mentioned the wierdo PowerBook SCSI
| | connector, but I guess that's understandable).
| 
| As far as I'm concerned, "SGI = Stupid Goddamn Idiots" re: all the braindamage
| on the SCSI bus per comments earlier this year.  Wrong ID for the host adapter,
| use of WD chip, inability to support a 6 meter SCSI bus with 4 devices, extreme
| sensitivity to cable impedance, etc.

Umm, where did you get the idea that there was something magical about
using some ID (I assume you mean 7) for the host?  Just because a lot
of people happen to use it doesn't make it 'correct'.  I have posted
here several times why we use 0.  The short summary is 'it was easy'.
The longer answer is that it can actually (very) slightly improve
*overall* system performance in a multiple target system (in a single
target system it doesn't matter what you do, of course), although that
testing came long after the decision to use 0.  Certainly none of the
SCSI standards ever came close to specifying/recommending an adapter
ID, since they supported multiple initiators from the first SCSI
standard (not SASI, of course).

I don't know what you have against the WD chip, or why it
matters to you, but see a long series of discussions about
2 months ago on comp.periphs.scsi on various SCSI chips for
my comments on the advantages and disadvantges of the WD 33C93
chip series.

I *personally* have used a 6 meter overall cable length on a number of
different SGI systems (with 1-7 targets).  I do hope you allowed for
the internal cable length (obscenely long in the predator chassis!).

Any high speed SCSI bus (single ended, at least) will be sensitive to
cable impedance.

If you believe you have legal configurations that don't work,
call support and beat them over the head about it until they
make it work, or show you that something isn't in spec!

| NO such problems with HP, Sun, Amiga, DEC, and Mac equipment on any of multiple
| systems (and the bad experiences with SGI SCSI is on more than one platform).

Then by all means, get it fixed.  I hear about most of the
SCSI problems on the ESD platforms, and a fair number on the
ASD platforms, and I know that *many* people have 7 devices
per bus working just fine, at least some with full length
cables (sometimes even exceeding the specs, although that
is pretty iffy).

I'm sorry to hear you have had more problems with our equipment than
with our competitors (after all, I own stock in SGI), but without more
details, I don't know what is different.

By the way, I've heard you complain more than once on comp.sys.hp about
the lack of partitioning, and other HP problems (and similarly on the
Sun newsgroups) , so I assume you aren't just bashing SGI for the hell
of it, and are really having problems.  I haven't heard from you on
comp.sys.sgi about SGI SCSI problems, as far as I can remember though;
have you at least contacted the support folks?  What hardware
platforms, and what kind of problems have you had?

I've been running 5-7 SCSI devices on every SGI system I've had (4D/20,
25, 35, Indigo, r4k Indigo) for long periods of time, with no problems;
similarly I've set up many in the labs, and in or test setups.  These
were all ESD products, and I can't speak from quite so much experience
on the power series, but I know it works there also.
--
Let no one tell me that silence gives consent,  |   Dave Olson
because whoever is silent dissents.             |   Silicon Graphics, Inc.
    Maria Isabel Barreno                        |   olson@sgi.com