The db2 backups are taking using TSM API client. In order to
remove/delete these files from TSM, the deletes must be initiated from
DB2 API.

For example,
If NUM_DB_BACKUP = 3
Step-1: All backup images <= 3 days will be in active state.
Step-2: All backup images > 3 days will be marked inactive state and
the retention period kicks in now.
Step-3: All backups will be retained for "x" days after marking it
inactive.
Step-4: All backups past "x" days will be marked as expired backups.
Step-5: All backups marked expired will be deleted by TSM expire
inventory.

After Step-2, DBA script may run db2adutl to delete the backups and
it's related log files (Or) Run a script to automatically delete
backups and logs using db2adutl command.

After Step-4, TSM should run expire inventory to remove expired
objects.
Check the Management Class settings and Backup/Archive Copy Group
settings for retention and expiration periods.

Please read this Redbook titled "Backing up DB2 with IBM TSM":
http://www.redbooks.ibm.com/redbooks/pdfs/sg246247.pdf

The pdf comes with scripts to automate the process of deleting backups
and log archives.

Another article on managing backups in TSM:
http://www.databasejournal.com/features/db2/article.php/10896_3330171_1

Regarding the files, history file will provide information on active,
inactive and expired objects. The db2adutl tells you what's in TSM. The
information between history file and TSM is different because files are
not being delete from TSM. We have to run db2adutl to delete these
files from TSM.

- Vijay