Do as Kelly suggests...

When we moved a server out of one 3494 with 3590 B1A drives into a different
3494 with 3590 E1A drives,
basically the same sort of action...
we just
set up the new library
set the next pool of all our diskpools to nothing...
took the old storage pools and renamed them to blah_old
defined the old name storage pools again  (you will use your new device
class name)
set the next pool of all our diskpools back to the proper storage pool name
and you're good to go...
we waited for a majority of the data to natrually expire out of the old
library, then set the next pool of the blah_old names to point to the
new/same/you_get_the_idea name and set the migration value down low and let
TSM move the remaining data.

was really really smooth
we just had to have both devices attached for about 6 weeks because most
data bases are archived daily with a 35 day retention...


later,
        Dwight