background: my company uses a rotating 4 week backup plan, where sets of tapes are changed every week, and recycled every 4th week. there are no monthly or yearly backups. each week contains 6 daily differential backups and one full backup. our backup set is 87 gigabytes, and daily differentials vary between 6 gb and 8 gb. the backup device is a Sony TESLA-11000 changer, with an 8 tape DDS4 magazine, giving us a weekly native capacity of 140 gb. with hardware compression, we're using about 45% of our capacity. media server is a Windows 2003 standard edition domain controller, backing up a handful of windows and unix servers.
as of about three weeks ago, any tape that is filled during a backup is marked "Infinite - Don't allow overwrite", despite being placed in a media set with a three week overwrite protection. media protection level is full, and overwrite method is set to recycle first. there are no events, alerts, or any other indications of a problem on the media server.