SUMMARY: Help -- SCSI transport failed: reason 'data_ovr'

From: Andrew Patrick (
Date: Fri May 03 1991 - 11:01:09 CDT

On Apr 22, 11:25am, I wrote:

| I am having problems with a SPARCstation 1+ generating SCSI errors.
| Configuration:
| Sun 4/65 (SPARCstation 1+)
| SunOS 4.1.1 (Rev B) (recently upgraded from 4.0.3)
| I have recently upgraded this machine from 4.0.3 to 4.1.1, and added a
| Wren VII drive at the same time. The machine is now generating SCSI
| transport errors at irregular times.

I received a few replies from the list, most of which suggested that I
shorten my SCSI bus (I estimate it to be 14 feet). This is a bit of a
problem since I already have 18 inch cables between the shoe boxes, so
I would have to go to new shoeboxes that hold multiple drives, or
shorten the cable from the CPU to the first shoebox.

One person suggested that these problems can be caused by the SCSI bug
not being terminated in the PIZZA BOX (CPU housing). Remember that I
have no internal drives. The suggestion was that a terminator should
be inserted into one of the 2x25-pin connectors used for internal
drives, and that a MAC terminator just barely fits. My MAC users
didn't know what I was talking about, so I never tried this out. It
does look like there are 3 yellow terminators on the left-front of the
CPU board, however, so I don't know if this suggestion is correct. Has
anyone ever heard of this?

The solution I adopted was to re-build my kernal to turn off
Synchronous SCSI. I remembered reading about possible problems with
Sych SCSI on other machines and with noisy cables, so I gave this a
try. Since running only Asych SCSI, I have not seen any more errors.

I also contacted the 3rd party supplier for the disks and tape drive.
They confirmed that the bus should already be terminated on the CPU
board, so this should not be the problem. They also suggested that
either Sun OS or Exabyte do not support Synch SCSI and 8mm tape
drives. This seems to make some sense because my worst errors were
when trying to backup the disks to the 8mm tape drive. Has anyone else
heard of incompatibilities with Synch SCSI and 8mm tape units?

In summary, I am running Asych SCSI and things seem to be working

Andrew Patrick, Ph.D.       Department of Communications, Ottawa, CANADA
                    "The interface IS the program."

This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:06:13 CDT