How to know a jukebox drive is not used by a session

[bertigo]

I want to start labeling a tape during a backup with 6 sessions which use my 4 LTO2 drive in a jukebox.
But I want to start to label when a drive is free from the backup sessions.
(After a while, it remains 2 sessions and I manually release the labelling process)

What is the best to do that by script?

by nsrjb or by lookin in the daemon.log

 

[speculos]

You can use nsrmm (without args):
if a drive is free: "(nothing) mounted on .."
if a drive is not free: "tape xxxxx mounted on .."