Yes, I am pulling from the media set with 6-day overwrite protection.
Yes, 3 other jobs share the media set. Its a Friday Job: Week 1 Friday through Week 4 Friday. There are 4 total jobs, 1 per week. There used to be only 4 tapes, 1 for each job. This worked as expected for the past year. In anticipation of filling up the tape, I added another 4 tapes to the media set a month ago. There are now 2 pieces of media in that set in the loader at any one time. (The remaining 6 are kept off-site.) The new tapes are being used because the jobs have overwritten them occasionally.
The job runs fine, however, after the first tape is filled up, it is marked as Infinite Overwrite Protect, and placed back in the media set that has 6-day overwrite protect. The job then mounts the 2nd available tape in the media set normally. After the job successfully completes, the 2nd tape is placed back in the correct media set, however its overwrite period is normal: 6-days.
This problem only started to happen once the job began to span to the 2nd tape, about 3 weeks after I added the 4 additional tapes to the media set.
Windows 2000 SP4
BE 9.1 Rev 4691
HP SSL1016 Autoloader (16 slots, 1 drive)
LTO2 tapes