I have been struggling with this for quite some time now. We are experiencing an extremely high number of tape/backup failures on our servers, and have not been able to track down the source of the problem. We are currently running:
Proliant DL380 servers
Compaq AIT 100 drives using Sony SDX3-100C tapes
Win NT Server
Veritas Backup Exec 7.3 and 8.2(?) (dont feel like running back to the farm at the moment..) :)
Event viewer logs show numerous ID 7's and 11's. Mainly ID 11: 'The driver detected a controller error on .....'
Backups usually hang the server until we yank the drive, or do a hard-reboot.
We have good availability of drives, and have been able to switch them out. However, we did find that on one of our drives that was residing on one of the worst servers (backup wise) the eject button was stuck depressed. (might cause long-term damage to drive/tapes maybe?)
We have leaned more to a batch of bad tapes, due to the fact that we can get a good backup with different tapes. However, the tapes that are reported good on one server, are reported bad on another and it is very unpredictable as to what tapes are good where. All Veritas documentation that I have found points to bad media, and bad headers on the tapes. We have to lean away from SCSI controller errors, due to the fact that this is happening on more than one server and is not an isolated problem.