We used some existing backup tapes to run diagnostics with the tape drive's tools, which destroyed the Media ID. Now BackupExec does not recognize the tapes, sees them as new media with a new Media ID. Is there any way to tell BackupExec that the tape in the slot is an existing media already in the database, i.e. restore the physical tape's Media ID to match the corresponding media already in inventory?
None that I know of. Generally, vendor hardware diagnostics are destructive to the data on the tape, so you wouldn't be able to restore from it anyway.
I would delete the old info from BE (retire the tape, then delete it).
You can certainly run a label job on the "new" media if desired to change the label.
If you are going to re-use the tape label, make sure you remove the old media id from BE by associating the label with the Retired Media Set and then right-click and delete. This will remove any backup sets which are associated with the old media id. If you do not retire the old media id before re-using the label with the new media id, then backup sets associated with the old media id will be present in BE.
We prefer not to delete the tape as it is important to keep the tape's statistics. That's why it would be useful to re-link the tape in BE to the physical tape, to maintain the statistics association. We knew the vendor diags would erase the data, just didn't realize we'd lose BE inventory link.
Sorry but I think you are going to have to delete the existing tape records from BE and then use the tape erased by OEM tools as if it is a new tape as we do not have a mechanism to re-associate after activities like this.