On old DEC StorageWorks arrays, you need to access the vt420 console and clear the invalid cache after a forced reboot. To do so, use a vt420 console on the storage array. If you need help, use ? or the HELP command.
CLEAR INVALID_CACHE THIS
CLEAR INVALID_CACHE OTHER
--> UNIT HAS LOST DATA
CLEAR LOST_DATA D101
Now the array should be in an optimal state, and your OpenVMS system should be able to access it.