Well, Raminder!

No, there is not a copy of the dbbackup on-site. That is why you perform,
let's say 1 or 2 full dbbackups once a week and incrementals every night.
Also, that is where the LOGMODE of ROLLFORWARD comes into play which would
allow you to restore the db to its most current state.

When you send tapes off-site that does include the dbbackup tape as well,
along with a copy of the volhist and the devconfig files. Dbbackups are
controlled with certain volhist commands for example, query volhist
begind=date etc...update volhist volume_name dev=device class
location=DRsite ormstate=vault

Hope this helps a little,

Demetrius Malbrough
TSM Consultant