SF for DB2/HA has a number of additional integration components with DB2 including:
The DB2 agent for VERITAS Cluster Server, which starts up DB2 in the event the active node goes down.
Concurrent I/O, and API through which DB2 communicates with VxFS to achieve superior performance
Management tools to allow checkpointing of a database for disk-based recovery.
Reporting tools to map from database tables to volumes, LUNs, even physical spindles.
There is more of course, but that's a start.
Regards,
Scott