According to the definition provided by the official VMware website, Quiescing is a process by which data stored on a physical or virtual machine is temporarily optimized to make a snapshot of the disk in anticipation of a backup.
This process is aimed to eliminate all the elements which can modify the information stored during the backup.
Performing backup using Quiescing avoids problems to the restore of SQL Server databases or to the rollback of the Update Sequence Number (USN) during the restore of Active Directory.
HOW TO ACTIVATE QUIESCING ON URANIUM BACKUP
Specify IP and Server Access credentials:
Choose the Quiesce guest file system option: