portability of tar tapes

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3 total messages Started by Cazier Fri, 06 Jul 1990 14:13

#358

Author: Cazier
Date: Fri, 06 Jul 1990 14:13

10 lines
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From: cazier@mbunix.mitre.org (Cazier)

How portable are tar tapes from one machine to another. My experience
has been that tar within a vendor's site is portable but to try to
carry a tar 1/4" tape from one vendor to another --- that's another story.

The only thing I've had luck with is 1600 bpi reel tapes written in cpio -
which is definitely not friendly to the casual user.

Volume-Number: Volume 20, Number 106

Re: portability of tar tapes

#365

Author: Henry Spencer
Date: Sat, 07 Jul 1990 23:39

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From:  henry@zoo.toronto.edu (Henry Spencer)

>From: cazier@mbunix.mitre.org (Cazier)
>How portable are tar tapes from one machine to another. My experience
>has been that tar within a vendor's site is portable but to try to
>carry a tar 1/4" tape from one vendor to another...

It is necessary to distinguish two issues here:  the tar format, and the
physical recording format.  The latter is whether you can get data off
the tape at all; the former is whether you can understand it.

Tar format is, if anything, significantly more portable than cpio, because
there has basically been only one version of tar format (plus some recent
upward-compatible extensions), whereas there have been several (different
and incompatible) versions of cpio.  The one problem that comes up now
and then is byte-swapping, due to broken hardware/drivers in certain
manufacturer's systems (I won't mention any names, except SGI :-)),
but a simple run through `dd conv=swab' solves that.

Physical recording format, especially on quarter-inch cartridges, is
another can of worms entirely.  There are too many different quarter-inch
recording formats to conveniently count, and new ones keep popping up.
If the recording format of the originating system is incompatible with
that of the reading system, it doesn't matter whether you're using tar,
cpio, ANSI standard magtape format, or whatever -- you *cannot* read
that tape.  Mercifully, there is basically only one format per density
on half-inch tape, and likewise on 8mm, and the appalling mess of floppy
formats settled down considerably when IBM's formats stomped all the
others (well, most of them, we won't mention Apple...) into oblivion.
Unfortunately, as I recall there are two formats on DAT, which isn't a
good start for a new technology.

                                         Henry Spencer at U of Toronto Zoology
                                          henry@zoo.toronto.edu   utzoo!henry

Volume-Number: Volume 20, Number 113

Re: portability of tar tapes

#370

Author: David Dick
Date: Mon, 09 Jul 1990 19:01

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From:  drd@siia.MV.COM (David Dick)

>From: cazier@mbunix.mitre.org (Cazier)
>How portable are tar tapes from one machine to another. My experience
>has been that tar within a vendor's site is portable but to try to
>carry a tar 1/4" tape from one vendor to another --- that's another story.

The trouble with 1/4 inch tapes is not tar format, but format
of recording data on the tape: there are QIC-11, QIC-24, and QIC-150
(and maybe others).  I'm not even sure that having QIC-11 or QIC-24 
is even sufficient.  However, I suspect all the QIC-150s are the same.

David Dick
Software Innovations, Inc. [the Software Moving Company (sm)]

Volume-Number: Volume 20, Number 118

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