To clarify CERN tape management, we have free empty tapes in so called supply tape pools.
Then, every user tape pool with user data has a value of partial tapes set to (for example) 1 and the supply column specifies from which tape pool new tapes should be taken.
For example:
userpool1 partialtapes=1 supply=supply_LTO8
This means that if userpool1 needs more tapes, the other script (I can share it with you) will then move 1 free LTO8 tape from tape pool supply_LTO8 to the tape pool userpool1.
Best regards,
Vladimir