Archive 2150S behaves erratically under SCO SysV/386 3.2

[j chapman flack]

The system: SCO Open Desktop 1.0.1 UFE (System V/386 3.2),
	    Adaptec 1540A SCSI host adapter
	    one Archive 2150S QIC tape drive, SCSI ID 2
	    one fixed disk, Seagate ST1201N, SCSI ID 0

What it does:  The 2150S seems to like to respond to commands the SECOND
time.  For instance, I pop a tape in the drive and say "tape load".  The
command returns, successfully, immediately, and the drive has done nothing.
The light remains off.  I type exactly the same command a second time,
the light comes on, the drive whirrs, and the tape is loaded.

Similarly, I then do a find ... | cpio ... to write on the tape, and a
screenful of file names flies by (about a blocksize worth, I guess) and then
cpio gives me a write error and exits.  I repeat exactly the same command
again, the same file names whiz by, then the drive whirrs into action and the
command executes through to completion successfully.

But SOMETIMES things work the FIRST time.  I haven't found a pattern.

"tape status"  ALWAYS  shows:

     status :
soft errors : 0
hard errors : 0
  underruns : 0

no matter what.  The man page lists messages like "Beginning of tape,"
"Write protected," "No tape," etc.  I get the above non-message under all
circumstances.

If I do a tar to a non-write-enabled tape, the file names whiz by on my
screen and the command completes successfully.  The tape just never moves,
is all.  (The FIRST TIME I try it, I might get a "write error" message, but
that's just the same message I get the FIRST TIME with a write-enabled tape.)

There's more.  I've been trying to use the no-rewind-on-close device to put
multiple files on one tape.  (What fun is a 150MB tape otherwise?)  My idea
has been to write a small "header" file, then tar something, say, then
another header file, tar something else, etc.  I could write a little shell
script to read the header file and then either tar in the tarchive or skip
it with a "tape rfm" and read the next header, etc.  (If there already exists
a utility for doing this, I'd like to hear about it.)

But when I put, say, a tarchive on the tape, and then write a little header
file, in MOST cases it works right and a "tape rfm" at the beginning of the
tarchive will skip it and the next read gets the header file.  BUT SOMETIMES
IT DOESN'T!  The little header gets appended to the end of the tarchive, so
"tape rfm" skips BOTH of them and the next read FAILS.  tar, of course, now
finds rubbish at the end of the tarchive.

What the Dickens is going on?  Is the SysV SCSI tape driver this buggy?  Is
it a SCO problem?  Is my tape drive busted?  (I got it used....)  What do I
need to make it work?
-- 
Chap Flack                         Their tanks will rust.  Our songs will last.
chap at art-sy.detroit.mi.us                                    -MIKHS 0EODWPAKHS

Nothing I say represents Appropriate Roles for Technology unless I say it does.