See my response to this much earlier post (& there have been many more!):
https://www-secure.symantec.com/connect/forums/how-find-out-total-capacity-backup-tape-netbackup
***EDIT***
& one I nearly forgot, despite saying I wouldn't, is James' response to this post:
https://www-secure.symantec.com/connect/forums/media-list-question
