If your tape library has Barcode reader support, you can run
omnimm -repository_barcode_scan "Library Name"
which will return something lile
Slot [side] Medium type Medium Label (ID)
================================================================================
=======================
1 Data Protector [XLN601L2] XLN601L2
2 Blank [XLN602L2]
3 Blank [XLN603L2]
4 Blank [XLN604L2]
5 Blank [XLN605L2]
6 Blank [XLN606L2]
7 Cleaning tape [CLNU00L1]
Final report: 7 cartridges out of 7 successfully scanned.
Redirect the output to a file, and, on UNIX, 'grep' for Blank' or 'Unknown', in Notepad, you need to physically identify the media
In a situation like this, native DP probably does not have the Granularity that you are looking for