Step 4. Specify Guest Processing Settings

If you want to back up Azure VMs that are currently running, you can configure guest processing settings at the Guest Processing step of the wizard. These settings allow you to specify what actions Veeam Backup for Microsoft Azure will perform when communicating with the guest OSes.

Particularly, you can specify the following guest processing settings:

Application-aware processing. For Windows-based Azure VMs running VSS-aware applications, you can enable application-aware processing to ensure that the applications will be able to recover successfully, without data loss.

Application-aware processing is the Veeam technology based on Microsoft VSS. This option can be applied only to the Windows-based Azure VMs that support Microsoft VSS. For more information on Microsoft VSS, see Microsoft Docs.

Guest scripting. You can instruct Veeam Backup for Microsoft Azure to run custom scripts on the processed Azure VM before and after the backup operation. For example, Veeam Backup for Microsoft Azure can execute a pre-snapshot script on the VM to quiesce these applications. This will allow Veeam Backup for Microsoft Azure to create a transactionally consistent snapshot while no write operations occur on the virtual disks. After the snapshot is created, a post-snapshot script can start the applications again.

Limitations and Requirements

When creating transactionally consistent backups, Veeam Backup for Microsoft Azure uses the Azure Service Bus service to stop and start applications running on the processed Windows-based Azure VMs. To ensure proper communication of the backup appliance and the guest OSes, all Windows-based Azure VMs for which you plan to enable guest processing must have the 443 network port opened.

In case firewall rules configured for the Azure VMs do not allow inbound and outbound access using the 443 port, you must allow HTTPS traffic over 443 port for <FQDN>.servicebus.windows.net, where <FQDN> is the name of the Service Bus namespace used by the Veeam backup service.

To find the Service Bus namespace name, do the following:

Log in to the Microsoft Azure portal.
Select the Azure service where the backup appliance belongs.
Choose the resource group associated with the backup appliance.
On the Resources tab of the Overview page, type type==Service Bus Namespace in the search field and press [ENTER] on the keyboard.

The Service Bus namespace name will be displayed in the Name column of the resource table.