From: Neil R. Smith (neils@ariel.met.tamu.edu)
Date: Mon Jun 24 2002 - 18:58:54 EDT
What does "mt -f [ntape device] seod" do?
Experiment: Tru64 5.1A
> mt rewind (only one tape device: a COMPAQ DLT7000)
> tar cf /dev/ntape/tape0_d1 dir1
> tar cf /dev/ntape/tape0_d1 dir2
> tar cf /dev/ntape/tape0_d1 dir3
> mt rewind
> mt -f /dev/ntape/tape0_d1 seod
> tar cf /dev/ntape/tape0_d1 dir4
Tapex -m says there's only 3 files on the tape.
Plus:
> mt rewind
> mt -f /dev/ntape/tape0_d1 fsf 3
> tar tf /dev/ntape/tape0_d1 gives 'no data'
BUT!:
> mt rewind
> mt -f /dev/ntape/tape0_d1 seod
> mt -f /dev/ntape/tape0_d1 bsf 3
> mt -f /dev/ntape/tape0_d1 fsf 1
> tar tf /dev/ntape/tape0_d1 will read the dir4 tape archive
AND
> mt rewind
> mt -f /dev/ntape/tape0_d1 seod
> mt -f /dev/ntape/tape0_d1 bsf 5 (!?)
> mt -f /dev/ntape/tape0_d1 fsf 1
> tar tf /dev/ntape/tape0_d1 will read the dir3 tape archive
This is maddening, at least in part because I can't seem to locate
comprehensive documentation on EOF writes and how/when they
are implemented by utilities like tar and vdump/vrestore. I have
more familiarity with other unix flavors wherein each utility
or mt 'fsf' or 'bsf' always leaves you on the end-of-tape side
of an EOF ready to read or write.
Anyone know what's going on here?
Thanks, -Neil
-- Neil R. Smith, Comp. Sys. Mngr. neils@ariel.met.tamu.edu Dept. Atmospheric Sci., Texas A&M Univ. 979/845-6272 FAX:979/862-4466
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