[2043] in linux-scsi channel archive
Re: scsi-problem (phase change ?)
daemon@ATHENA.MIT.EDU (Leonard N. Zubkoff)
Sun Jun 22 13:46:08 1997
Date: Sun, 22 Jun 1997 10:34:31 -0700
From: "Leonard N. Zubkoff" <lnz@dandelion.com>
To: ash@ash.ccc.de
CC: groudier@club-internet.fr, linux-kernel@vger.rutgers.edu,
linux-scsi@vger.rutgers.edu, ncr53c810@colorado.edu
In-reply-to: <Pine.LNX.3.95.970622124030.25953A-100000@mdma.ash.de> (message
from Hauke Johannknecht on Sun, 22 Jun 1997 13:05:32 +0200 (MET DST))
Date: Sun, 22 Jun 1997 13:05:32 +0200 (MET DST)
From: Hauke Johannknecht <ash@ash.ccc.de>
urgl.
hmm, how can i describe my scsi-bus ...
i will go from one terminator to the other ...
first end (inside computer)
|--- Quantum LPS with terminators installed (passive ?) --->
---> IBM DCRS (no way to terminate this one ... <g>) ---->
---> NCR 810 --->
---> external cable (80cm) --->
---> external 4-device-box --->
---> Seagate ST1600N --->
---> Sanyo CD-ROM --->
---> HP 6020i --->
---> end of external box --->
---> external active terminator ---|
makes a total of no more than 2 meters ...
(1) If you run even normal Fast SCSI-2 (10.0 mega-transfers/second) on your
SCSI bus, you should have *active* termination at both ends. Some
configurations *might* get away with passive termination, but at the
first sign of any problems you should immediately move to active
termination.
(2) Ultra SCSI (20.0 mega-transfers/second) is even more stringent. If I
recall correctly, you are allowed 3 meters cable length only if you have
at most 4 devices, and 1.5 meters if you have more. The cables must also
be built to much more stringent specifications. This doesn't apply to your
configuration since the 53c810 isn't Ultra-capable, but it's here for
reference.
With this configuration, I'd suggest it's time for a second SCSI bus.
Leonard
