HP 9144A, other stuff

From: Frank McConnell <fmc_at_reanimators.org>
Date: Thu Nov 4 09:55:48 1999

John Ruschmeyer <jruschme_at_hiway1.exit109.com> wrote:
> I don't recall seeing 3rd-party 9145 tapes (32-track), but for the 9144
> you want 3M DC600 IOTAMAT-format.

3M used to sell the 15MB/150-foot 9144-compatible flavor as the DC615HC.

A former employer tried to get me to use those once, which is how I
found this out. After trying one for a while, I declined. Here's
why:

There are two or three layers of "formatting" on these. The 3M tapes
had the lowest layer, the one that must be done at the factory because
it requires the full-width head that can write block delimiters.

The HP tapes have the next layer as well, the data that is read by the
tape drive and which contains usage and block sparing information. If
you have an HP3000 w/9144 the VINIT FORMAT command will write this,
but in my experiments at the former employer I found it took
noticeably longer to format the 3M tapes (perhaps it was testing the
tape blocks to figure out which blocks need sparing? I don't know).
I didn't think it was worth the couple of bucks we would save per tape
for someone to sit on his or her butt waiting for this to happen. But
once you do this they do work. And I have no idea how to do this step
with a 9000.

The third layer? Well, on a 3000 you access the 9144 as though it is
a removable-pack disc drive. Fortunately the 3000 has the concept of
accessing a disc serially: you use the VINIT SERIAL command to label
the "disc" (actually the tape) as a serial volume. I don't think this
applies to 9000s but I think for the 9000s you are supposed to pipe
tape data through tcio (which buffers the tape drive I/O in a way that
reduces wear and tear on the drive and tape).

-Frank McConnell
Received on Thu Nov 04 1999 - 09:55:48 GMT