A more carefull look at the E-mail I sent showed that the original problem I
had writing to a tape was with the raw device - /dev/rst0. Here I'll include
it again:

Jan 14 07:00:50 dakkon /netbsd: st0(ahc0:4:0): illegal request, data = 00 00 00 00 00 00
Jan 14 07:00:50 dakkon /netbsd: st0: cannot set selected mode
Jan 14 07:01:17 dakkon /netbsd: st0: bad request, must be multiple of 512

simmons@dakkon[34]% tar cvzf /dev/rst0 edge
edge/
edge/OTE.cardlist
edge/OnTheEdge.cardlist
simmons@dakkon[35]% tar (child): can't write to /dev/rst0 : Input/output error


---------  Received message begins Here  ---------

> From thorpej@lestat.nas.nasa.gov Fri Nov  7 14:03:06 1997
> X-Authentication-Warning: lestat.nas.nasa.gov: localhost [127.0.0.1] didn't use HELO protocol
> To: "Gerald C. Simmons" <simmons@darykon.cet.com>
> Cc: port-i386@netbsd.org, current-users@netbsd.org
> Subject: Re: AIC7XXX driver - No Tape support for writing? 
> Reply-To: Jason Thorpe <thorpej@nas.nasa.gov>
> From: Jason Thorpe <thorpej@nas.nasa.gov>
> Date: Fri, 07 Nov 1997 10:34:14 -0800
> Sender: thorpej@nas.nasa.gov
> 
> On Thu, 6 Nov 1997 09:15:42 -0800 (PST) 
>  "Gerald C. Simmons" <simmons@darykon.cet.com> wrote:
> 
>  > I've done some further investigating and I'm suspecting there is no "write
>  > support" in the Adaptec AIC7XXX drivers, or at least the 2842VL.
> 
> Um, how can there possibly be "no write support"?
> 
>  > I tried the following:  "tar cvf /dev/st0 <directory>" with my Archive 150
>  > attached to an AHA2842VL controller. The Tape LED came on, tar went about it's
>  > business with NO ERRORS, but the drive NEVER made a move. It was as if tar was
>  > dumping to /dev/null.
>  > 
>  > I checked all the -current files for the AIC7XXX and ahc_isa.c drivers for any
>  > changes since 1.2.1. There were only context changes - bus_space vs. bus_io.
>  > 
>  > Does anyone know if this is a known missing feature?
> 
> The "ahc" driver doesn't know (or care) what type of device its talking
> to.  That's be beauty of SCSI :-)  Also, if the ISA "ahc" couldn't write
> to tapes, it would be a problem for the EISA and PCI "ahc" drivers, too,
> since it's really all the same driver.
> 
>  > I can READ from tapes, just can't write!
> 
> I suspect it's an artifact of not using the "raw" tape.  Try using /dev/rst0.
> 
> The block device interface to tapes hasn't really ever worked (the semantics
> of implementing it are just too hairy, for one), and probably ought to just
> be removed.
> 
> Jason R. Thorpe                                       thorpej@nas.nasa.gov
> NASA Ames Research Center                            Home: +1 408 866 1912
> NAS: M/S 258-6                                       Work: +1 650 604 0935
> Moffett Field, CA 94035                             Pager: +1 415 428 6939
>