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From: dremu@emf.net (The Mu-Meister)
Newsgroups: comp.periphs.scsi,comp.unix.bsd.freebsd.misc
Subject: Re: Bizarre SCSI problem (3 disks work, 4 don't) (2940UW/Quantum Atlas II)
Followup-To: comp.periphs.scsi,comp.unix.bsd.freebsd.misc
Date: 4 Feb 1997 15:33:38 GMT
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Alan Judge (ajudge@maths.tcd.ie) spoke thusly:
: I have a really odd (in my experience, at least) SCSI problem. The setup is
: a PC (running FreeBSD 2.2-BETA) containing an Adaptec 2940UW. No internal
: disks. The external 68-pin connector is connected to a case containing 4
: Quantum Atlas II disks. Inside the case, the 4 disks are chained together
: on a ribbon cable. The case is terminated with an external active
: terminator, and the 2940 termination is set to automatic.
: The 4 disks are numbers 0..3. When *any* three disks are connected to
: the ribbon cable, everything works fine; I can access and use the
: disks. When all four are connected, the SCSI system fails quite
: quickly. The usual symptoms are a lockup where one of the disk
: activity lights will remain on. Eventually FreeBSD times out and
: things unlock and an error is generated. This problem can occur as
: early as the initial probing of the disks.
I betcha you disabled the termination on the drive via a jumper. What you may
well need to do - I had to on a chain of CDC drives once I won't describe due
to embarassment now - is remove the resistor packs as well. (This assumes your
drives have them!) If they're present, even though the +5V side isn't
connected (ie the unit isn't terminated) the ground side is still connected
and it hoses the SCSI bus.
Just a thought.
--
home: dremu@emf.net http://www.emf.net/~dremu
that's doctor emu ftp.emf.net/users/dremu
work: aaron_shephard@peoplesoft.com http://www.peoplesoft.com
My other computer is a Linux box
and of course, the views expressed herein are those solely of the indivudal
and in no way alleged to indicate those of PeopleSoft or other PeoplePeople