VMware Tools Quiescence

When you back up or replicate a running VM, you need to quiesce or ‘freeze’ the VM to bring its file system and application data to a consistent state. Data quiescence is crucial for highly-transactional applications. It helps create transactionally consistent backups or replicas and guarantees safety of application data.

To create consistent backups and replicas for VMs that do not support Persistent VSS Snaphots (for example, Linux VMs), Veeam Backup & Replication uses the VMware Tools to freeze the file system and application data on VMs before it creates a backup or a replica. VMware Tools also allow you to create backups and replicas for Microsoft Windows-based VMs that support Microsoft VSS. For this, VMware Tools use VMware VSS component. For details on the supported OSes and quiescence features, see the VMware documentation.

To create transactionally consistent backups or replicas of VMs that do not support Microsoft VSS, you must define the following settings at the job level:

Enable VMware Tools quiescence. For more information on how to enable VMware Tools quiescence, see vSphere Settings.
Specify scripts that will bring applications to a transactionally consistent state before freezing and to the initial state after freezing VMs. For more information, see Pre-Freeze and Post-Thaw Scripts.

Note

By default, Veeam Backup & Replication uses application-aware processing when both VMware Tools quiescence and application-aware processing are enabled. If some VMs cannot be quiesced with application-aware processing or it is disabled for specific VMs in the job (the Disable application processing is set for VMs in the job settings), Veeam Backup & Replication uses VMware Tools quiescence to prepare these VMs for backup or replication.