About the Veritas VSS provider for vSphere (NetBackup for SQL Server)
Veritas recommends that you use the Veritas VSS provider. To truncate logs, you must use the Veritas VSS provider to create full VSS backups. The VMware VSS provider creates copy-only backups, which cannot be used as a basis to truncate logs.
When the Veritas VSS provider is installed and NetBackup starts a virtual machine snapshot, VMware Tools calls the Veritas VSS provider to quiesce the VSS writers for a file-level consistent backup. If log truncation is enabled in the policy, the logs are truncated when the VMware snapshot is complete.
Note:
The Veritas VSS provider must be installed separately.
See Installing the Veritas VSS provider for vSphere (NetBackup for SQL).