cazier@mbunix.mitre.org (Cazier) (07/06/90)
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
henry@zoo.toronto.edu (Henry Spencer) (07/08/90)
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
drd@siia.MV.COM (David Dick) (07/10/90)
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