So I just got off the phone with a Dell NetVault tech who cleared up the "bug" I ran into.
I have a pretty basic setup - run a full backup on a file share once a week, and run incrementals every night. Both the full and incrementals are set to expire & be discarded after 1 full backup. Backup 101 I would think.
The problem I ran into is that the backups were not expiring as I expected so my tapes were filling up. The incrementals would show up as expiring "never" despite the configuration, and the fulls would now show "discard after 0 full backups." So the incrementals were not expiring, and therefore the dependent full backups were not expiring either.
It turns out that the "Discard after X full backups" has no effect on incremental backups. I'm told this is by design, and a change from previous versions. The only way to automatically discard incremental backups is by date (e.g., 1 day, 1 week etc).
The problem is, of course, I'd never want to expire my incrementals unless I know that my full backup completed successfully, superseding those incrementals. What happens if my weekly full backup failed? I'd lose the week of changes if I set my incrementals to expire after 1 week (after the next full backup should have occurred). I guess I could either leave the incrementals with no expiry and go in and manually expire them, or I could set them to expire after 1.5 or 2 weeks and just make sure I override that if the full backup failed for any reason that week. Either option requires manual intervention when really none should be required.
Am I the crazy one, or should this just be a very basic feature of any backup software? 10.0.0.0.1