More tape problems

[Jeff Siegal]

I recently inquired about poor performance on a Cipher microstreamer.

Well, we now have a TU78 (delivered yesterday), and being curious, I
decideded to play with someone else's TU78 here.  The poor performance
shocked me.  The is supposed to be a FAST tape drive.

I was unable to get anything I would call satisfactory using cat, or
cp (I didn't try dump).  The same TU78 works beautifully on a VMS
system (swapped the cables), but when used from Unix (4.3BSD), it
seems to spend more time sitting there than writing.

An interesting thing I noticed, which may have something to do with my
Cipher problem, is that when writing to the /dev/mt0 device, it seems
to write lots of little records (presumably wasting a lot of tape),
but when writing to /dev/rmt0, it seems to work more slowly, but write
larger records.

Does anyone have any idea how to get satisfactory performance out of a
tape drive under Unix?  Help!!

Jeff
-------