Prerequisite to Enable virtual machine quiescing
By default, the Nutanix Guest Tools (NGT) feature is disabled for a VM running in a Nutanix cluster. Nutanix recommends installing NGT and in some cases have pre-freeze and post- thaw scripts on the VM when you are planning to take application-consistent snapshots that is enable virtual machine quiescing.
Note:
Application consistent backups require version 9.1 or later for the NetBackup media server version.
To install NGT and add scripts, see, here.