We have Backup Exec 9.1 running on one of our 2003 DC's connected to an HP Storage Works Ultrium 460 which takes LTO2 200/400 tapes, with a remote agent on our other 2003 DC and a remote agent / exchange agent on our exchange 2003 Server. Our set up was working fine for months until we starting noticing that when a restore job had been run the job engine would stop responding and all the backup exec services needed to be restarted before any further scheduled backup jobs would take place, though this wasn't really a great issue.
We then started to have a problem with the "Insert Overwritable Media" message whereby at a different point each night the current tape would be ejected and a new tape requested even though our entire backup job is much less than the uncompressed capacity of the tape. After running HP tape diagnostics on the device and finding no issues and that it had the latest firmware installed, we updated Backup Exec to the latest available service pack. This temporarily fixed the problem until I did a small restore of user data from a tape the next week and the problem started again. I tried reapplying the service pack again but this made no difference, although whenever I tried running a test job this would always go through no problem. I took the decision to completly uninstall backup exec and the remote agents and start with a fresh install and a newly configured job. After installing all of the required components back on the servers I ran a test job - this was over 200GB, so I reduced the selection to miss backing up some non-essential data and its now set to back up approximatly 185GB - this test run worked. I imported a tape which was overwrittable and the media set has no overwrite protection and append is infinite, but the tape was ejected after only 1.9GB and a second tape requested. I cancelled the job when I arrived the next morning and because it had been a week since the last backup I decided to run a one off job to an external USB hard disk, partially to have a backup of our data and also to see if it would go through. This worked fine and backed up the 185GB with just a few skipped files. I decided to try the tape again during office hours and it reached 139GB this time before asking for another tape, I had a spare which wasn't part of the daily cycle so inserted it and the backup continued then the first tape was requested once the verification stage was reached. I really need to advice as I have already taken the drastic step of uninstallation and reinstallation and according to tape diagnostics there is nothing wrong with the drive and all our tapes are major vendor branded ones although we don't have enough to use 2 per day and we shouldn't really need to as we are using them at less than capacity