I have two DPM units sharing the same Tape Library (Dell ML6000). This has been working for over a year. The DPM-2 "owns" the Library, and shares it with DPM-3.
DPM-3 now shows the Library as offline. I've tried to Rescan and no change. Rebooted both the Tape Library and DPM-3, no change in status.
We did have a tape jamb in one of the three drives on the ML6000 that correlates to when DPM-3 went offline. The tape library is working fine on the other DPM.