Howard -

Presumably, you would have tested the ability to read the old LTO2
tapes at the OS level, before committing to TSM use, via tapeutil or
the like, so as to assure technology usability.  Did that work, or
turn up any anomalies?

Technote 1269453 indicates that LTO2 tapes should be usable in an LTO4
environment, providing that the stipulated actions are undertaken.
The technote doesn't say whether any path redefinition is needed to
make it work, however.  I'd use SHow LIBRary to do the most reveal on
what TSM thinks of the arrangement.  Beyond that, you may have to
contact TSM Support.

   Richard Sims