Streaming tape problem in 6300

[Joel M. Cook]

I have a Wangtek streaming tape controller and the appropriate
60MB drive.  This combination works quite nicely under UNIX
on my 6386WGS.  I wanted to change from a 30 MB hard disk
on my 6300 (ROMBIOS 1.43, MSDOS 3.3) to a 20 MB.  The 30MB
disk is RLL and the 20MB is ST506.  To do this, I thought to
install the streaming tape unit on the 6300, back up the
18 or so MB on the disk, change the disks, and put the
contents back onto the 20MB disk.  I installed the
STU,after some playing around with interrupts and DMA stuff, and
it seemed to work fine as evidenced by the successful installation
and checkout with the diagnostics diskette.  However, when
I do a complete backup, the tape writes until it reaches
the end (long before 15MB have been transferred), and then
gives me an "unrecoverable write error" and stops.
If anyone knows why this is so, I'd appreciate being
told.  SInce it's a 60MB
tape, this seems to be unreasonable
behavior.  More importantly, if anyone knows how to fix
the problem, I'd be even MORE appreciative.  I don't know
if it's a fundamental problem with using this STU in a 6300, a
problem trying to back up an RLL disk, or just brain-damaged
software!  Thanks in advance for any help.

			Joel Cook