Ok .. I have my answer. It's a curious one, but plausible.
My thanks to all those who responded.
The original question:
> 2 years ago, we bought an "ArchiveST 4000DAT" 4mm DAT drive for use in
> doing backups. Up until recently, I had it hooked to a SS running
> SunOS 4.1.3. In that context, it was accessible as expected via
> /dev/rst1 (low density), /dev/rst9 (med.), /dev/rst17 (high), and /dev/rst25
> (compression). Everything worked generally well.
>
> Now, the admin machine is a SS5/85 running Solaris 2.4. I added the device,
> did a reboot -r, and Solaris obligingly detected it and added the device
> and reconfigured the /device and /dev directories. Now it claims the
> device is /dev/rst5 (it was always set to SCSI 5, even before), /dev/rst13,
> /dev/rst21, and /dev/rst29. HOWEVER, the only one which actually talks to
> the physical device is /dev/rst5, the low density setting. The other three
> settings all respond with "no tape loaded or device is offline", even when
> rst5 happily senses and works with a tape.
The solution:
I finally broke down and called Maynard, the company who made the box,
(although the drive itself is a Connor?) and here's what the tech.support
guy told me:
1. Sun OEMs the Archive Python Helical Scan 4mm DAT drive, and their version
has slightly different firmware. *This* is the drive which Solaris
2.4 knows primitively, to which it can self-configure. This is the
drive which can be accessed as /dev/rmt/Nlb, /dev/rmt/Nmb, /dev/rmt/Nhb,
and /dev/rmt/Ncb.
2. The 3rd party flavor of the drive can *only* be accessed via Nlb, however,
the compression is firmware controlled and permanently enabled.
So, by using the same "dump" parameters I was using before,
(d=61000 and s=10240) I'm still getting the compression I expected
and the 2G capacity, even though Solaris may think it's a "low
density" device.
Curious, but my experiences seem to bear it out .. my backup process seems
to be working just as it always did, so I suppose I shouldn't have complained.
Again, my thanks to those who responded:
mshon@sunrock.East.Sun.COM (Michael J. Shon {*Prof Services} Sun
Kevin.Sheehan@uniq.com.au (Kevin Sheehan
pasken@thunder.slu.edu (Robert Pasken)
Stephen P Richardson <spr@myxa.com>
Scott Erickson <erickson@binky.ICS.UCI.EDU>
<signed>
H.Modell
_____________________________________________________________________
Howard Modell (206)662-0189
Adv.Computing Technologist/2 POBox 3707, m/s 4C-63, Boeing D&SG
howie@warlok.ds.boeing.com Seattle, WA 98124-2207
<A HREF="http://xavier.ds.boeing.com/users/howie/"> HSM </A>
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