Resource cannot fully utilize

[John_Wan]

Recently, I found that there are always a tape drive free even there are many pending job in the database. 

Refer to the picture, TLD 2 & 3 are located at the same site and share the same resource pool. Perviously, it will use all drive during the daily backup. However, now as you can see one of the tape drive is not loading. 

I am sure that it is not the drive problem because the emtpy drive will swap between other drive. Could you please let me know if any setting related to it? For example, reserve a drive for some purpose. Or else, how can I trouble shoot it. Thanks.

[jim_dalton]

Lots of reasons...lack of usable media, limit on stunit via maximum concurrent write drives setting, lack of demand from a running job are some of the popular ones.

[Marianne]

Check for orphaned resource allocations. 
Run this command from cmd:

nbrbutil -dump
(command is in <install-path>\veritas\netbackup\bin\admincmd)

Post output of bottom part (MDS Allocations).

This command is a quick way of releasing all allocations (only do it when no backups/restores/duplications are active):

nbrbutil -resetAll