Tape Drive Parms

[Jack F. Vogel]

In article <1132 at msa3b.UUCP> kevin at msa3b.UUCP (Kevin P. Kleinfelter) writes:
>Does anyone have the magic numbers for a 6157-002 tape drive?
>I'm looking for the fun stuff that the backup command needs like
>tracks, density, etc.  I have looked in the AIX doc, which assumes that
>your tape drive doc provides the info.  I have looked in the tape
>drive doc, which assumes you are running in a DOS environment, and
>you have software which knows.
 
>WHat are the numbers, and where are they documented (where did I fail
>to look)?

Kevin, the place you want to look I believe (the problem is that I have
looked in the docs for the next release and not the AIXPS/2 manual) is
the man page for backup itself.

The trick is in the way in which the streaming drive writes to tape, it
writes in a serpentine fashion on the 9 tracks. Therefore when you specify
the length with the -s flag use the tape length multiplied by 9, i.e.,
600*9 = 5400. Now on density I am not completely sure, the tapes I have
say "12500 ftpi" and I am not sure if that is equivalent to bpi or not
but as a test I would suggest setting -d 12500 and see how it works,
basically these numbers are used by backup to calculate how much data
it can write on a tape and not really anything to do with the hardware,
so if you get a reasonable amount on the tape fine; otherwise it will
get a hardware error before it finishes.

If anyone out there thinks this is a braindead way for software to
behave, and why it couldn't just rely on hardware in its operation, I
agree wholeheartedly :-}!!

Disclaimer: my opinions only!

-- 
Jack F. Vogel			jackv at seas.ucla.edu
AIX Technical Support	              - or -
Locus Computing Corp.		jackv at ifs.umich.edu