Using DP 9.07:
I ran into an issue with switching a filesystem backup to virtual environment on a VM that is a document server: and getting a higher available than the required setting.
[Major] Virtual Machine 'VM_NAME': Insufficient disk space on datastore 'DATASTORE' for snapshot creation (required: 10, available 16) ...
The error was reporting just the datastore where the OS of the VM presided. It has 4 disks across 3 different datastores and one of the disks used 1.8 TB of a 2TB Datastore Volume. That datastore was showing 9.94% free.
I didn't want to drop to 0% for Free Space Required in the VE Settings for the backup spec as I prefer not to have a datastore feel up 100%.
P.Louage replied to the ESX VM Backups error Data Protector (insufficient disk space) post with:
"... For the VStorage (VEPA) you must specify a 0-100% (steps of 10%) free space check when creating a backup specification. The % is part of the barlist in C:\ProgramData\OmniBack\Config\Server\BarLists\VEAgent"
The files in there are the backup specs and are the same name as the spec.
I opened up the VM spec in question, found the "free_space_required=10" changed 10 to 8 and saved the file. I then ran the job without issue.
I submitted a documentation feedback on the session report asking for them to add all datastores in the message or more verbage that not all of a VM's datastores are shown in the message.
Hope this helps someone else save some time.