From: ADSM: Dist Stor Manager on behalf of Andreas Almroth [Head Office - IS 
Consultant]
>We are about to implement TDP for Oracle on one of our databases, and
I'm now trying to plan the best configuration for this.
One question that came up was how we efficiently generate a backupset to
a tape volume to be stored offsite.
My understanding is that TDPO backs up the data to the named file space
in tdpo.opt, and that when generating a backupset the whole active file
space will then be copied to the destination volume/s. But as all files
are unique, all RMAN backups that have not been expired still exist as
active.
=============

All backups created with an API interface (such as any of the TDP agents) 
cannot be inserted into a backupset; backupsets can only contain data backed up 
with the B/A client.

That said, if you shut down Oracle, run a cold backup of the data, and use the 
B/A client to back up that dump with a 29-day retention, all backupsets 
containing that data will only contain the latest dump.

--
Mark Stapleton