Can I backup TSM database via D2D2T?

Hi, I am new to TSM.

Now I am thinking how to backup TSM database to tape,
but I have been told TSM database can only backup to new tape.
Does that mean, if I need to keep 1 week backup on tape, I will need to prepare 7 tapes?

If so, can I backup TSM database to file on disk firstly, then migrate it to tape, same as backup a general file?
with this way, do I still need 7 tapes to keep 1 week backup?

Thanks.