SUMMARY: Unable to use DEC tape/disk on Sun

From: Magnus Kempe (
Date: Thu Jul 08 1993 - 04:14:43 CDT

About one week ago, I asked for help wrt to using a DEC tape
device on Sun machines (the original article is appended below).

I have gotten four responses (three e-mail, one phone-call :-).

The answer is that it is possible, one has to change (SunOS 4.1.3)
/sys/scsi/targets/st_conf.c to add a description of the tape
device, and some jumpers must be appropriately set on the device
(see below).

The sad part is that DEC was unable to give us any kind of useful
information. We returned the device. Meanwhile, three responses
indicated that they successfully use HP's DAT device, and gave me the
necessary SCSI entry (again, see below). We decided to go for the HP
device (which apparently stores, with compression, up to 8 GB; compare
with DEC's max claim of 5 GB). Finally, someone told me that DEC merely
puts its name on and sells HP's DAT devices, a claim I am unable to verify.

Wrt the disks, we verified with an independent vendor that DEC's disks
(RZ-26) should work OK.

Magnus Kempe

From: (Uwe Bolte)

Sample edit of /sys/scsi/targets/st_conf.c (and then make a new kernel):

/* HP DAT HP35480A Bo 22.02.93 */
        "HP35480A", 2, "HP", ST_TYPE_EXABYTE, 1024,
        (ST_VARIABLE | ST_BSF | ST_BSR),
        5000, 5000,
        { 0x00, 0x00, 0x00, 0x00},
        { 0, 0, 0, 0 }

From: Wolfgang Bauer <>

Guess at an entry for a DEC tape device:

   "DEC Dat-Streamer",3,"DEC",ST_TYPE_EXABYTE,1024,
   { 0x00, 0x00, 0x00, 0x00 },
   { 0, 0, 0, 0 }

[MK: the one who called me on the phone said that it was important
 to keep the first field as an array of _exactly_ 8 bytes, e.g.

One message asked for information about the SCSI cabling. We used
what we got from DEC, and it worked.

In article <>, I wrote:
: Has anyone positive experience with DEC devices on a Sun server?
: We haven't and neither DEc nor Sun support has been able to give
: us any useful advice. Here's the situation:
: We have tried to use DEC's tape and disk SCSI-2 devices on our Sun
: 670 MP, SunOS 4.1.3, without success.
: Hardware: 4mm, 4GB tape, TLZ-06 (with compression); fails (description
: below). The disks seem to work OK (RZ-26/RZ73). Pedestal: BA-350. The
: controller is the internal SCSI controller of our server (the length of
: the cable is not the problem), the other devices on same controller work
: perfectly well.
: Software: SunOS 4.1.3, "dump" is the Backup Copilot version.
: Problem description: sometimes, dump succeeds, sometimes it stops with
: the following message:
: DUMP: NEEDS ATTENTION: Cannot open lglsun:/dev/nrst18.
: Do you want to retry the open?: ("yes" or "no")
: Replying "yes" lets dump continue (and sometimes ask the same question
: again), until it finally succeeds with its work. This is of course
: unacceptable, since we're aiming at unattended backups during the night.
: % mt -f /dev/nrst18 status
: Exabyte EXB-8200 8mm tape drive:
: sense key(0x6)= unit attention residual= 0 retries= 0
: file no= 0 block no= 0
: (note that it says "Exabyte" while it isn't; the kernel doesn't
: recognize the device; at boot-time, the device identifies itself
: correctly, with "Vendor 'DEC ' Product 'TLZ06")
: There is no correlation with size of the disk partition or specific disk
: partition (or time of day :-). The dump parameters used are:
: 0ubdsf 126 61000 12000 (it seems not to matter in this context).
: Our dumps work perfectly well with the Exabyte and QIC devices. Should
: the kernel be somehow configured for the new device? how? or is it
: that either DEC or Sun relies on non-standard SCSI operations/fails to
: provide SCSI standard operations? is it hopeless?
: We would appreciate to hear of positive experiences with DEC's disks,
: at least (so that the day won't be totally lost).

Magnus Kempe			"Reason ... is the glory of our nature."
Magnus.Kempe @				-- Elihu Palmer

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