Dell NetWorker 19.9 Administration Guide

Task	Save operations attribute	Behavior
To enable VSS.	Blank	Leaving the attribute empty results in NetWorker software automatically using VSS.
To completely disable VSS.	VSS:*=off	VSS backups will not occur and backing up the following save sets for a NetWorker client resource yields these results: DISASTER_RECOVERY:\ save set Backup fails at the beginning of backup operation. All save set Backups fail.
To use a hardware provider or a specific software provider for a NetWorker client backup.	VSS:VSS_ALLOW_DEFAULT_PROVIDER=yes	A backup provider is selected based on the following default Microsoft criteria: If a hardware provider that supports the particular volume on the NetWorker client is available, it is selected. If no hardware provider is available, then if any software provider specific to the particular NetWorker client volume is available, it is selected. If no hardware provider and no software provider specific to the volumes is available, the Microsoft VSS system provider is selected. Windows Bare Metal recovery backups always use the Windows VSS system provider even if the VSS:VSS_ALLOW_DEFAULT_ PROVIDER=yes command is specified for the NetWorker client resource. Windows Bare Metal Recovery provides more information about Windows Bare Metal recovery backups.

VSS commands