Application-aware processing is the recommended option for VMs running applications that support Microsoft VSS — Microsoft Exchange, Microsoft Active Directory and other. If you cannot use application-aware processing (for example, you cannot access the VM over the network and deploy Veeam's runtime process on it, or you want to process a Linux VM and want the backup or replica to be consistent at the application and file system level), you should enable Microsoft Hyper-V guest quiescence. Microsoft Hyper-V guest quiescence will put applications on the VM to a consistent state before the VM snapshot is created.
If you use Microsoft Hyper-V guest quiescence, Veeam Backup & Replication will quiesce the VM but will not perform application-specific actions required for proper backup and restore of VMs running highly transactional applications. Application-specific steps include the following tasks:
- Applying application-specific settings to prepare applications for VSS-aware restore at the next VM startup
- Truncating transaction logs after successful backup or replication.
Enabling Both Quiescence Options
You can enable both options for VM quiescence. Such scenario is recommended if you add Microsoft Windows and Linux VMs to the same job. In this case, all VMs will be processed in a transactionally consistent manner — either with application-aware processing or Microsoft Hyper-V guest quiescence.
In such scenario, Veeam Backup & Replication will process VMs in the job in the following way:
- Veeam Backup & Replication will first attempt to use application-aware processing to prepare VMs for backup or replication. If Veeam Backup & Replication manages to quiesce all VMs in the job with application-aware processing, it will not use Microsoft Hyper-V guest quiescence.
- If some VMs cannot be quiesced with application-aware processing or application-aware processing is disabled for some VMs in the job (the Disable application processing is set for VMs in the job settings), Veeam Backup & Replication will use Microsoft Hyper-V guest quiescence to prepare these VMs for backup or replication.
To enable both options:
- At the Storage step of the wizard (for backup) or Job Settings step of the wizard (for replication), click Advanced.
- On the Hyper-V tab of the Advanced Settings window, select Enable Hyper-V guest quiescence.
- At the Guest Processing step of the wizard, select the Enable application-aware processing check box.
- When configuring advanced option for individual VMs, select Try application processing, but ignore failures. You can also select the Disable application processing option for VMs that you want to process with Microsoft Hyper-V guest quiescence.
If you enable application-aware processing and Microsoft Hyper-V guest quiescence but do not select the Ignore application processing failures option, Veeam Backup & Replication only use only application-aware processing for the job.