I've spoken with support on this one but wasn't really able to get anywhere so putting it out to the community.
I've got a job backing up some file servers to disk that runs at 12:05am each day. It takes between 3-4hrs. Then I have a GFS schedule doing Weekly / Monthly backups to tape of this job.
This is the output I would normally get..

Occasionally this is happening.. (too frequently, results in the job spanning longer than the 24hr window before the disk job kicks off again)
Attempts to run at the scheduled time.. fails..

Then runs again once the disk backup has completed but it now decides its going to use a vbk map resulting in large backup file (twice the usual backup size) + twice the copy time

This all may be expected behavior in which case please explain to me how I can
1. Run a GFS job using reverse incremental backups without the above failing behavior occurring
2. Stop a disk job cancelling a tape job
Many thanks for any insights here