Problems interfacing SCSI disk to Sun 3/50

[homsy at icsi.berkeley.edu]

I currently have a Sun 3/50, and a SCSI disk which I am trying to
interface to it.  The disk is a CDC 94211 (otherwise known as Imprimus or,
more recently, Seagate).

The problem is as follows:  The first time a SCSI command 0 (a "Test Unit
Ready" command, I believe) is sent to the disk, the busy light comes on on
the disk and stays on, and the SCSI bus will no longer talk to the disk.

I have had some success with the Sun standalone diagnostic program, by the
following method:  When diag says, "reset scsi bus...", I have to manually
power cycle the drive.  When the drive reinitializes, a command completion
error is generated, and diag requests the sense.  Following this, diag
reissues the test unit ready command, and this time it succeeds!
Following this, diag works beautifully:  I can scan for defects, format
the disk, partition it, label it, verify the label, perform seek, read,
and write tests succesfully, etc...

When I try and boot vmunix, when the si device driver is initializing, the
busy light on the disk comes on and stays on, and the kernel goes happily
on its way, not realizing there's a disk there.

If I reinitialize the disk after booting (by power cycling the disk), and
then try a dkinfo, the same behavior results:  The busy light comes on and
stays on, and dkinfo reports a command completion error, followed by a
bunch of "no such device" and "no such disk" error messages.

I get the impression there's a simple fix for all this, but I'm too
inexperienced to know it yet...

Suggestions, anyone?

--George Homsy
homsy at icsi.berkeley.edu
(415) 642-4274 x 174 (w)
(415) 641-7470       (h)