Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!decwrl!ucbvax!PAN.SSEC.HONEYWELL.COM!thompson
From: thompson@PAN.SSEC.HONEYWELL.COM (John Thompson)
Newsgroups: comp.sys.apollo
Subject: re: Exabyte Drives on DN4500
Message-ID: <9008171707.AA01793@pan.ssec.honeywell.com>
Date: 17 Aug 90 17:07:38 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 51



> At SR10.2, there are some SCSI tape device files included in
> /dev as part of the standard release. These do work with an
> Exabyte, although you may have toset your SCSI unit ID on
> your tape drive to match those used by Apollo ... 
We had no problems (plug and play).

> I don't how their device driver deals with multiple tape drives
> (say a SCSI internal cartridge and an external Exabyte).
Seems to handle it ok.  Note below for SCSI terminator info.

> The SR10.2 release has a /dev/rmts9 and /dev/rmts13 set
> of device files in addition to the /dev/rmts8 and /dev/rmts12
> files. Maybe the first set are for SCSI unit 1, and the
> others are for unit 0?
The SCSI cartridge tape is still /dev/rct8 (12), unless I'm
sorely mistaken.  The cartridge tape is SCSI device 0.  The
8mm tape drives are (should be) devices 1 and 2.  The /dev
device files for these are
        /dev/rmts8           unit 1, rewinding
        /dev/rmts9           unit 2, rewinding
        /dev/rmts12          unit 1, non-rewind
        /dev/rmts13          unit 2, non-rewind
As I understand it, there are 3 places that terminators can
exist from the WDC-7000 controller.  They are on the cartridge
drive, on the controller next to the cartridge cable, and
on the last unit in the external SCSI chain.  If memory serves
me, you should have exactly 2 terminators in place.  In other
words, you should take the controller's terminators OFF if you
have both a cartridge drive and an external SCSI chain.  (This
is from the Apollo Technical Bulletin ATB-03-65A, which states 
that "both (the PAIR on the controller) terminators will always
be in unless the system has both an internal SCSI C-tape and an
external SCSI device."

Incidentally, I read from somebody here (4 months ago?) that you
can set up more than 2 SCSI 8mm drives.  If you check the Omniback
installation, it appears that 'unit X rewind' is minor device
number '4X' and 'unit X non-rewind' is minor device number 32+4X.
I haven't tried setting up more than 2 8mm drives on a node, and
so don't know if this'll work or kill the node or something 
in-between.

John Thompson (jt)
Honeywell, SSEC
Plymouth, MN  55441
thompson@pan.ssec.honeywell.com

As ever, my opinions do not necessarily agree with Honeywell's or reality's.
(Honeywell's do not necessarily agree with mine or reality's, either)