Formatting a tape?

[Jaime]

I have a DLT tape drive in a FreeBSD system.  With one of the tapes, I
can get "tar -cvpf /dev/sa0 -C / ." to work.  With all the other
tapes, I can't.

Is there some kind of formatting process that I need to do?  I tried
"mt fsf 1" from this page:

http://www.freebsd.org/doc/en/books/handbook/backups-tapebackups.html

This didn't seem to work, though.

Any help is appreciated,
Jaime

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