Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!think!mintaka!bloom-beacon!primerd!barry
From: barry@primerd.prime.com
Newsgroups: comp.sys.mac
Subject: Re: Help Needed on SCSI Hang
Message-ID: <160700097@primerd>
Date: 14 Mar 90 02:47:00 GMT
References: <160700094@primerd>
Lines: 59
Nf-ID: #R:primerd:160700094:primerd:160700097:000:2906
Nf-From: primerd.prime.com!barry    Mar 13 21:47:00 1990


Thanks for your lengthy reply posting.  I realized after I posted to
c.s.m that a better place would have been c.s.m.h and I reposted
there.

Your comment about the Maxtor powering the bus was interesting.  It
was my intention to configure the Maxtor so that it was always
externally terminated and I planned to remove the jumper, if present,
that caused the Maxtor to power the bus.  When I was fiddling with
the drive, I was short of jumpers, so I'm pretty sure I would have
removed any jumpers that weren't needed. Unfortunately, I can't be
sure of how the Maxtor is configured w/o removing it from the case,
which I'm loathe to do because of the hassle involved in installing
it in the case (a real exercise in "just fits" engineering).  Next
time, I'll be sure to keep a written record of how the disk is
configured.

Based on your comment, I tried a test when I got home today.  I
powered up the Maxtor, used it, dismounted the partitions, and then
turned the Maxtor off.  I then used the SE for other things for about
5-7 minutes, and then restarted.  There were no hangs or other
problems with this restart.  Thus, as you surmised, the problem might
be capacitors in the Maxtor, not the SE.

So, it appears that I can reboot the SE if the Maxtor has been off
for more than about 5 minutes.  The pain factor of this regimen isn't
high enough to justify removing the Maxtor from the case, inspecting
the jumpering (which I think is already set to not power the bus),
and reinstalling the Maxtor.

When I said that I thought I used to be able to restart w/o problems
after turning off the Maxtor, I probably was recalling incidents
where the Maxtor had been off long enough to avoid the problem.  The
jumpers haven't changed since I configured the Maxtor.

I didn't mention this in my original posting, which was detailed
enough without this additional information, but I've got another
Maxtor 3280 that I use with my Mac IIcx at work.  The configuration
there is Mac <-> Maxtor <-> Syquest. I'm 99+% sure that the Maxtor at
work is jumpered the same as the Maxtor at home (I did them both the
same afternoon).  Yet, if the Maxtor at work is connected to the Mac
IIcx, the Mac IIcx won't boot unless the Maxtor is powered;  this
happens both when I use the Syquest as the terminator or use an
external terminator.

So, the Maxtor at home can be off when SE boots, but Maxtor at work
must be on when IIcx boots.  Is this due to difference in the Macs
or to difference in Maxtors?

Ain't SCSI fun?

Regards,
         Barry
------------------------------------------------------------------------
Barry Wolman                      | barry@s66.prime.com
Principal Technical Consultant    | 500 Old Connecticut Path
Prime Computer                    | Framingham, MA 01701
                                  | 508/626-1700, ext. 1100
------------------------------------------------------------------------