Exabyte and file positioning...

[Robert E. Toense]

There are three possible conditions for writing files on an Exabyte drive:

1) Beginning of tape,
2) Immediately following a write (no intervening motion), and
3) Immediately following writing a filemark (no intervening motion).

One of these conditions must exist or the write will fail.  In the
scenario described,

tar xf /dev/nrst0
mt -f /dev/nrst0 rew
mt -f /dev/nrst0 fsf 1
dump 4dsbf 54000 6000 100 /dev/nrst0 /dev/...

the dump does not follow one of the three conditions.  Exabyte drives DO
NOT work like 1/4" and 1/2" drives with regard to tape positioning and
writing.  Check the Exabyte manual for further discussion.

Robert E. Toense
(toense at cplxsys.ncsl.nist.gov)