VMware Quiescing 

Quiesces the VMs before taking the snapshot for application-consistent backup. VMware Quiescing should be enabled if you require application consistency for your backups. If you disable VMware quiescing for any of the VMs, then successful application processing cannot be guaranteed.

• In the VMware Quiescing page, Toggle the slider to the right to enable the VMware Quiescing for all the VMs selected for the backup. 

• If you don’t want to Quiesce the one or more VMs during the backup, you can disable the Quiescing for the individual VMs.