If the storage pool data is already on tape, I think you may be stuck
until you can get a second drive.
However, if you're doing reclamation by moving data to a disk storage
pool and then moving it back to the tape storage pool, you could get a
backup copy of the data by backing up the intermediate disk storage
pool before you moved the data back to tape. Depending on the amount of
data you have on tape, and the amount of time it will take you to get a
second drive, this could be an option. You would then have to make sure
that you backed up all of the other data before it migrated to tape.
This assumes that you don't have any data that is going directly to
tape, and your disk storage pool is large enough to handle one full
cycle of incremental backup data.

Elvin Peterson
S.C. Johnson Wax