Problems with restore (4.2BSD)

[lancs.sm]

When trying to do a restore, mounting the tapes in reverse order as suggested,
restore asked us for a tape which had been previously mounted.
After we mounted this tape - we got a HUGE number of diagnostics about files
being missing from the tape.
We tried it again in the forward order and it worked!
I guess it splits files between tape boundaries and doesn't realise not to
re-read a WHOLE tape after getting the tail end of a file from the previous
tape.