dump(8) verification ?

[Rick Lindsley]

A relatively reliable way to check even a multi-volume tape is to do a
dumpdir (or restore -t, depending on your flavor) and, using awk or
sort or something, obtain the highest number inode that was dumped.
Then restore that file, doing it the *dumb* way (starting with tape 1,
through tape n). This will force restore to read each and every tape
and finally restore the last file on the last tape. This doesn't verify
the data on every file, but it does verify that all the tapes are
readable, that the labels you put on the tapes are correct, and that
the data on the tape is in a recognizable format. This was the test we
used to use at a leading university (Hi guys) before we packed away the
last full backups of a semester for three years.

If all you are interested in is tape errors, however, then as someone
else mentioned, dd is a very fast way of doing that.

Rick Lindsley