> > ......  IFF there IS as way to do that, I want to find
> > out how.  Retensioning seems to be something overlooked in the
> > DLT tapes, but maybe be important for tapes that have sat for
> > years unused.
> 
> So an "mt -f /dev/mt0 retension" doesn not work on the TK series
> drives?

Nope.  AFIK, in the sources the retension and erase commands are
specifically not operational.  I even checked some old PDP11 ultrix
sources, and same there, too.

To me, that suggests the hardware does not support retension or erase,
in the traditional sense of the old 9 track reels or 1/4 inch streamer
cartridges.  That must be not a bug but a feature!

I have this nagging habit of wanting to retension all tapes before use,
and erase all tapes before an initial write.  Old habits die hard.
The TK50 transports just don't do that well.

>  Is there maybe a mechanical way to forward the tape (I am
> thinking maybe hacking an old broken TK50 drive to just have it spin the
> tape to the end, and then maybe stick it into a decent drive and let it
> rewind??

I don't know of a way to manually do it, although I did get a powered
up TK50 not on any interface to spin and roll the tapes, as a test.
It rolled it about half way out of the cartridge, at high speed, but
did not finish the retension.  Pressing the load button rewound it, OK.
That helps a little, but is not a best solution.

> My questions might be a little stupid, but I am concerned about keeping my
> old media alive as well.  Without finding a scsi card for my qbus vaxen, I
> have to rely on those old TK's for bulk sneakernet transport.  I do have
> everything on a network and can move things around that way as well, but
> it's much simpler to install off a tape than the network (albeit a lot
> slower) and since I only have a dialup internet connection, if I need to
> move a large chunk of data between a work machine and home to a vax an
> external tk is the way to go.

I can sympathize with that.  What I do, of late is to use a laptop
as a ferry machine to do that locally for home uploads, or keep a
cd writer at the office so I can write a cd and then unload it at home
off a PeeCee/Sparc/Mips *BSD box onto the VAXenfarm.

Still, tape is a perfectly valid mode.  Also, careful conservation
of what little tapes remain in circulation, is important.  That is
especially true for ancient UNIX historically important tapes, or
even the wierdo tapes like the TK50 thingies.....(:+\\....

Without rustling any feathers, I always was instructed to retension
every tape before use.  That accomplishes two things, 1) aligns
the tape on the reels, and 2) frees any sticking tape loops.
It also stretches the tape slightly, but that appears to be of
relatively minor importance compared to 1 and 2, above.  On the
single reel cartridges, (e.g., the DEC DLT things --- TKxx cartridges
and probably later DLT things, too), I am finding that they stick
slightly and won't properly unroll freely out of the cartridge.
That is bad karma for tapes.  A TK50 transport will slow down
as that happens, then generate a loud click as the motor speed
decrease is sensed and it shuts down.  If that happens, you are
in for a long TK50 dismantling, if the rewind won't start.
Sometimes it does, but often it just will not do that.  On the
slide in trays, that is not so bad, but in those darn outboard
scsi boxes, it takes considerable time to clear the bits out of
the way to get to the screws to release and slide out the tape
transport to pull its lid and twist the tape a few degrees to
unlatch it.  The only way I have found to clear the sticking,
reliably is to reach into the mechanism and rotate the takeup
reel a few degrees to accomplish that unlatching of the
mechanism.  Grumble, grumble.....(:+\\...

Anyway, questions aren't dumb or stupid, if they get you down the
road.  There are a lot of collective wisdome gurus de VAXenspeak
about the list, and I learn a lot from them every day!

Bob