these are normal messages; to verify, check the relevant section of bptm logfile, ie i looked for just section '9466'. the bptm -U is trying to umount all tapes, the tapes are in use and being written at the time; then you should see EXIT STATUS 0 at the end ie no errors/problem even though the tapes aren't ready for unload.

bash-2.05# cat log.100206|grep 9466
00:00:58.731 <2> bptm: INITIATING (VERBOSE = 1): -U
00:00:58.732 <2> db_byid: search for media id CH5961
00:00:58.732 <2> db_byid: CH5961 found at offset 158
00:00:58.745 <2> db_lock_media: unable to lock media at offset 158 (CH5961)
00:00:58.745 <2> bptm: EXITING with status 0 <----------


Unfortunately scouring thru NetBackup logs can be like trying to decode Nostradamus' quatrains :P

..sometimes it's best to only go thru the logs if you're investigating a genuine problem, as there's sooo much stuff in the logs you'll chase your tail for days and end up convinced the billions of warnings/messages are problems. I used to dig around in the logs a lot but ended up chasing too many red herrings; can be highly frustrating.