Our backups are set to run at 20:00 Monday-Friday. However, the running time for the backup varies, with 7hours on one day, and 14hours on the next run. Looking at the starting times, the backup doesn't start until 21:00 on the 7hour jobs, and 04:00 on the 14hour jobs, even though a tape has been inserted during the daytime for the job to commence.
I can't see anything in the event viewer to indicate a problem.
Any ideas on how to resolve this?