You are running a NDMP backup, which, I believe, does not use Disk Agents, instead it does a dump of data from one media agent to another. I would have like to have see the full session report to confirm this
One Media Agent is the Sourse, and the other, which is running the tape drive, is the destination
Due to the NDMP catalog handling design, Data Protector caches the entire catalog on the NDMP
client before storing it to the Data Protector internal database (IDB).
Does the backup finish? If so, I would say that you are seeing Normal behavior