VM Backup

Veeam Backup for Microsoft Azure performs VM backup in the following way:

Veeam Backup for Microsoft Azure creates snapshots of virtual disks that are attached to the processed Azure VM.

Disk snapshots are assigned Azure tags upon creation. Values of Azure tags contain encrypted metadata that helps Veeam Backup for Microsoft Azure identify the related disk snapshots and treat them as a single unit — a cloud-native snapshot. For this reason, you must not delete any Azure tags whose names start with the word veeam.

Important

Due to Microsoft Azure limitations, you can apply up to 50 tags directly to a subscription. That is why Veeam Backup for Microsoft Azure is able to create a snapshot only if the tag limit is not reached for the subscription to which the processed Azure VM belongs. If the limit is reached, the operation will fail with a serialization error. For more information on subscription limits, see Microsoft Docs.

If you enable image-level backup for the backup policy, Veeam Backup for Microsoft Azure performs the following operations:

Launches a worker instance in an Azure region in which the processed Azure VM resides.

By default, Veeam Backup for Microsoft Azure launches worker instances using virtual networks created automatically. However, you can add specific worker configurations. For more information, see Managing Worker Instances.

Reads data from the created cloud-native snapshot using a shared access signature (SAS) URI, compresses the data and transfers it to the target backup repository, and stores it in the native Veeam format.

To reduce the amount of data read from virtual disks, Veeam Backup for Microsoft Azure uses the changed block tracking (CBT) mechanism: during incremental backup sessions, Veeam Backup for Microsoft Azure compares the new cloud-native snapshot with the previous one and reads only those data blocks that have changed since the previous backup session. For more information, see Changed Block Tracking.

Note

Veeam Backup for Microsoft Azure encrypts and compresses data saved to backup repositories. For more information on data encryption, see Data Encryption.

Deallocates the worker instance when the backup session completes.

If you enable the backup archiving mechanism, Veeam Backup for Microsoft Azure performs the following operations:

Launches a worker instance in an Azure region in which the target backup repository resides.
Retrieves data from the target backup repository and transfers it to the target archive repository.
Deallocates the worker instance when the archive session completes.

Veeam Backup for Microsoft Azure stores the backed-up data depending on the type of the virtual disk attached to the protected Azure VM:

Snapshots created for managed virtual disks are saved to the resource group to which the Azure VM belongs.
Snapshots created for unmanaged virtual disks are saved to the Azure storage account where the Azure VM resides.
Backups created for managed and unmanaged virtual disks are saved to the target repository.

For more information on Azure virtual disk types, see Microsoft Docs.