tar

[LAAKSONE at FINFUN.BITNET]

Please tell me what I'm doing wrong. I'm doing a backup with tar
of my files on a 4D/70GTB. I don't want to waste good tape so I
try to write the new files after the last one on the tape.
Iris man pages do not mention anything about the "-r" key which
should add the new files after the last file and tar is complaining
with the message "tar:blocked tapes cannot be updated" if I try to use
"-r". Ok, next try: I used "tar tf /dev/nrtape" to get to the last file
on tape and then I tried with "tar cv  files" to add the new files.
The man pages are saying for "c": Create a new tape; writing starts
at the beginning of the tape instead of after the last file. This option
assumes that you are at the beginning of the tape. What happens if I'm not at
the beginning?
No success the tape is first rewinded and the files are written at
the begining of the tanpe. To use just "tar v files" does not work either.

What should I do to add new files after the last file on a
cartridge tape?

Leif Laaksonen
Centre for Scientific Computing
ESPOO
FINLAND