Mate you need to upgrade to 6.x, but that aside.
The whole idea of netbackup is that it is meant to manage what goes where. You are not meant to care about which media is being used for what backup. Only that it is in the correct pool and has the correct retention period.
But if you want to know which backup in on which media then find the report which outlines the client backup time in regards to the media used ( I forget which one ). Then in the Backup, Archive and Restore window list the backup for the client in question. By already knowing the media used for the backup, you can then cross reference that with the filelist.
Please note, NetBackup will not overwrite a media until all images on the media are expired.
So, if you want to keep a backup for longer as a standard then set the retention in the policy schedule to a longer period. If you want to update the retention of a backup to be longer then originally defined, then run the images on media report and for the backup id ( Clientname_<10digit_number>) you want to hold longer issue the command ../netbackup/bin/admincmd/bpexpdate -recalculate -backupid <backup-id> -d <date>
NOTE : BE CAREFUL, The bpexpdate command has the ability to immediately delete images as well as extend their life. Using '-d 0' will expire immediately.
