Tape media

From: Jerome H. Fine <jhfinepw4z_at_compsys.to>
Date: Sat Mar 22 22:35:00 2003

>Gunther Schadow wrote:

> so I sorted through my last weekend's bait, hooked up my new HSZ40
> (with 50 GB in 4 StorageWorks boxes plus all sorts of tape drives,
> TSZ07, TLZ07, TZ68, and ~88) to my PC for FreeBSD. It's so much
> fun to read a 9-track reel from a FreeBSD PC (just too bad it doesn't
> have a transparent top cover to show off the reels).
>
> I have bulk-erased a bunch of TK50 tapes in the hopes that they
> would work as DLT III and IV tapes as well, but these drives
> still went into write-protect mode. Does anyone here know details
> about the DLT media? I mean it is a well-known fact (and I proved
> it to myself many times) that CompacTape I works just fine as
> CompacTape II. So why not as III and IV? Is it really the tape
> or might it be some notches on the cassette that are used to
> code the kind of tape?
>
> The problem is I didn't get any tape media for my nice DLT tape drives
> and this stuff is so darn expensive if bought new. Any ideas?

Jerome Fine replies:

Memorex used to have a list of all of the physical characteristics
of CompacTape / DLT tapes. I can't remember any of the actual
numbers, but I do remember the key information you require.

CompacTape I and CompacTape II were completely identical
in every detail - except for for the colour of the name on the case.
Usually The "CompacTape" label was brown; the "CompacTape II"
was usually blue. Oh yes, DEC charged a fair bit more for the tape
with the blue label. Both the TK50 and the TK70 used these tapes.
However, once a given drive started to write on a blank tape, it was
not possible to switch the tape to be written by the other drive. In
particular, the TK70 could read tapes written by a TK50 drive, but
the TK70 would immediately WRITE PROTECT itself as soon as
the tape was interested into the TK70. A bulk erase is required to
allow switching the tapes between the TK50 and the TK70 - as
your have already discovered.

As for the DLT III media, the physical characteristics were substantially
different from the CompacTape media. I am quite sure that the drives
which use the DLT media are unable to use the CompacTape media.
Likewise, the TK50 / TK70 drives are unable to use the DLT media.

DLT IV media are very different again from DLT III media.

Sincerely yours,

Jerome Fine
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Received on Sat Mar 22 2003 - 22:35:00 GMT

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