We all use available_media on a daily basis. I really don't understand why you don't want to use it?
The available_media script is a script that consist of NBU commands.
You can probably accomplish the same by writing your own scripts, but that would also be 'not supported' by Symantec in the sense that you cannot log a call if you need assistance with your script.
The nice thing about available_media is that it combines vmquery and bpmedialist output. This means that you can see amount of data already written to media that can still be appended to.
vmquery can only give you 'assigned' or not assigned - in other words empty or used.
Have a look at 'vmquery -a -bx' output, then combine output with 'grep' and 'awk' depending on what you need.
