How Backup Works

Veeam Backup for Microsoft Azure does not install agent software inside instances to retrieve data. To back up resource data, Veeam Backup for Microsoft Azure uses native Microsoft Azure capabilities. During every backup session, Veeam Backup for Microsoft Azure creates a cloud-native snapshot (for an Azure VM) or a BACPAC file (for a SQL database) for each resource added to a backup policy. The cloud-native snapshot is further used to create an image-level backup of an Azure VM, the BACPAC file is used to create SQL backup of a SQL database.

Azure VM Backup

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

1. Veeam Backup for Microsoft Azure creates snapshots of virtual disks that are attached to the processed Azure VM.
2. If you enable image-level backup for the backup policy, Veeam Backup for Microsoft Azure performs the following operations:

1. Launches a worker instance in an Azure region where the target repository is located.
2. The worker instance reads data from a cloud-native snapshot, transfers the data to a backup repository and stores it in the native Veeam format. Veeam Backup for Microsoft Azure encrypts and compresses data that you back up to backup repositories.

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 where 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 blob container.

For more information on the types of the virtual disks, see Microsoft Docs.

Azure SQL Backup

When processing a database added to a backup policy, Veeam Backup for Microsoft Azure can create a restore point of the database and transfer the point directly to a backup repository, or Veeam Backup for Microsoft Azure can copy the database to a staging server first, create a restore point and then transfer it to a repository. In the latter case, Veeam Backup for Microsoft Azure will also process all transaction logs of the copied database to create a transactionally consistent backup. This guarantees the consistency of the database state during recovery but could increase costs associated with cross-region data transfer.

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

1. [Applies if you plan to perform backup using a staging server] Depending on the type of the database, Veeam Backup for Microsoft Azure does the following:

• For an Azure SQL Database running on a SQL Server — creates a copy of the source database on the staging server using the Azure REST API. For more information on Azure SQL Databases, see Microsoft Docs.
• For a database located on a SQL  Managed Instance — creates a copy of the source database on the staging server using point-in-time restore (PITR) from the point made 10 minutes ago. For more information on Azure point-in-time restore, see Microsoft Docs.

To learn what differences SQL Managed Instances and Azure SQL Databases have, see Microsoft Docs.

2. Launches a worker instance in an Azure region where the staging server or source database is located.

3. Exports the database schema, indexes and constraints to a BACPAC file. For more information on BACPAC files, see Microsoft Docs.

4. Reads data from the BACPAC file on the worker instance, transfers the data to a backup repository and stores it in the native Veeam format.

Veeam Backup for Microsoft Azure encrypts and compresses data that you back up to backup repositories.

5. [Applies if you plan to perform backup of the Azure SQL Database using a staging server] Removes the copy of the source database from the staging server.

Related Topics

• Snapshot Chain
• Backup Chain
• Changed Block Tracking
• Retention Policy