Backup Exec 2012 SP4. The job backing up VMs from a VMware ESXi 5.5 cluster with Application GRT had been bugging me for weeks with error:
V-79-57344-38260 - Unable to create a snapshot of the virtual machine. The virtual machine may be too busy to quiesce to take the snapshot.
on one of the VMs which had previously been backed up just fine. For all other VMs it continued working as before.
I finally found the reason and thought I'd share it here, as it didn't figure in the search results I got when searching for this error.
The VM in question had been renamed in vSphere, but not in Windows, and the selection list of the backup job had not been updated. So Backup Exec tried to back up a VM which according to VMware did not exist, but a Windows host by that name did exist, had a Backup Exec agent installed, and even had a valid trust relationship. Apparently that situation confused Backup Exec to such a point it was unable to report the problem correctly.
After removing the VM from the selection list and re-adding it from the browse tree under its new name, it is now backed up fine again. The differing Windows hostname doesn't seem to bother Backup Exec. It even shows the Windows host as "backed up" in the All Servers pane.
Hope it helps someone.
