For some workload environments, reduce the size of the job database before upgrade
Following an upgrade to NetBackup 9.1, existing jobs for certain workloads are assigned an asset namespace to enable access control at an asset level. This process may take some time. You should reduce the size of the jobs database before upgrade. This action minimizes the amount of processing required to perform the association and minimizes the effect on web services performance. Very large job databases may see an alert regarding high heap space usage.
The affected workloads include: Cloud, Nutanix AHV, RHV, and VMware
For further details see the following article: