How about month-end exports?  You can keep them for as long as you need,
but there is the extra step of re-importing them to be able to restore from
them.

When I'm confronted by someone trying to do a "traditional"
full-incremental-incremental scheme with TSM, explain how TSM works,
starting out with, "Unlike every other backup program you've ever used,
TSM..."  (And I seem to have to use that speech a lot...)

Nick Cassimatis
nickpc AT us.ibm DOT com

Today is the tomorrow of yesterday.