On Thu, 14 Jun 2001, NetBSD Bob wrote:

> That does not often work.  If it does, then the retension was not
> really needed.  When the read stops in mid tape, with what apparently
> is a dragging of the tape (e.g., sticking of the tape layers together,
> as seems to be happening on the older tapes), I need something to force
> a high-speed tape movement.  A usual dd/tar/whatever read does not do
> that at high speed, in a continuous, forceful movement.  Mt appears
> to do that since it is just throwing away bits after reading.  Mt
> appears to spin the tape at maximum speed, thus giving it more
> momentum to get across the places where it is sticking slightly.
> This is after observing the actual tape movement on an open transport.
> A retension would be best, since it does not read anything from the
> tape, except look for the hardware end of tape.  But, DEC's wisdom
> did not seem to include that capabilty in the DLT transport
> mechanisms.  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?  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??
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.

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