Step 4. Specify Guest Processing Settings
If you back up Azure VMs that are currently running, at the Guest Processing step of the wizard, you can configure guest processing settings. These settings allow you to specify what actions Veeam Backup for Microsoft Azure will perform when communicating with the instance guest OS to create transactionally consistent backups.
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 about Microsoft VSS, see Microsoft Docs.
- Guest scripting. You can instruct Veeam Backup for Microsoft Azure to run custom scripts on the instance before and after the backup operation. For example, Veeam Backup for Microsoft Azure can execute a pre-snapshot script on the instance 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 instance volumes. After the snapshot is created, a post-snapshot script can start the applications again.
- Pre-snapshot script quiesces the file system and application data on the Azure VM guest OS. It brings the VM to a consistent state before Veeam Backup for Microsoft Azure triggers an Azure VM snapshot.
- Post-snapshot script brings an Azure VM and applications to their initial state after the snapshot is created.
Guest scripting option doesn't require the enabled Microsoft VSS. It can be applied both to the Windows-based and Linux-based Azure VMs.
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 Azure VMs. To ensure proper communication of the backup appliance and the VM guest OSes, Windows-based Azure VMs must have the 443 network port opened.
In case firewall rules configured for the Windows-based 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 to which the backup appliance belongs.
- Choose the resource group associated with the backup appliance.
- On the Resources tab of the Overview page, in the search field, type type==Service Bus Namespace and press [ENTER] on the keyboard.
The Service Bus namespace name will be displayed in the Name column of the resource table.