You presume there is some kind of logic in this business requirement.  This
is just someone's spin on DR to get the data in an alternate site not more
than 48 hours old the way I see it.

I do not understand why they would not just create a copy pool on a tape
library in the second SAN and connect the primary TSM server to the DR SAN
and the primary SAN.  Then they can see the tape drives from both.  Just
create a copy pool and perform Database backups twice a day (once to
primary, once to secondary).

This presumes the tape drives are on the SAN and not shared on the other end
unless a DR has occurred.  Otherwise, TSM to TSM server communications will
have to be put in place to share the drives.