Restore Windows IaaS Virtual Machines
You can protect your data by performing backups at regular intervals. Several backup options are available for virtual machines (VMs), depending on your use case, as described in the following table:
| Backup Option | Description |
|---|---|
| VM Backups | To back up Azure VMs running production workloads, use Azure Backup. It supports application-consistent backups for Windows and Linux VMs. Azure Backup creates recovery points stored in geo-redundant recovery vaults. During restoration, you can restore the entire VM or only certain files. |
| Azure Site Recovery | Protects your VMs against major disaster scenarios, such as a complete regional outage. You can configure Site Recovery to restore your applications within minutes by replicating to an Azure region of your choice. |
| Managed Snapshots | In development and test environments, snapshots offer a quick and simple solution to back up VMs using managed disks. A managed snapshot is a full, read-only copy of a managed disk. It is independent of the source disk and can be used to recreate a VM. Billing is based on the used portion of the disk. For example, if you create a snapshot of a 64 GB disk with only 10 GB of data used, you will be billed only for the 10 GB. |
How to Back Up VMs
Backing up Azure VMs with Azure Backup is simple and follows a logical process:
1. Create a Recovery Services Vault:
To back up your files and folders, create a vault in the region where you want to store the data. Also determine the desired replication type: GRS (geo-redundant) or LRS (locally redundant).
💡 Tip
If Azure is your primary storage point, use GRS by default. If it is not the primary point, choose LRS to reduce costs.
2. Define the Backup via the Portal:
Protect your data by taking snapshots at defined intervals. These snapshots, called recovery points, are stored in the vaults. If needed, you can restore the VM from any recorded point. A backup policy defines when snapshots are taken and how long they are retained. You can trigger a daily backup.
3. Back Up the VM:
The Azure VM agent must be installed on the VM for the backup extension to work. If the VM comes from the Azure Marketplace, the agent is already installed.
💡 Tip
VMs migrated from an on-premises datacenter do not have the agent installed. You must install it manually.
How to Restore VMs
Once the snapshots are stored in the vault, restoration is also simple. When you trigger the restore, the Backup service creates a tracking job and displays temporary notifications to monitor the process.
To restore a VM:
- Select the relevant VM in the Azure portal, then click Backup.
- Or select the recovery vault, then Backup Items.
- Choose File Recovery or Restore VM.
- Follow the on-screen instructions to complete the process.
Backup and Restore at the Azure Disk Level
A VM consists mainly of two elements: the compute server and the persistent disks. Both affect fault tolerance. In case of hardware failure (rare), Azure automatically restores the VM on another server. The VM restarts and becomes available after some time.
Azure Backup works with managed and unmanaged disks. You can create scheduled backup jobs, easily restore VMs, and define retention policies.
If you use premium SSDs, managed disks, or other types with the LRS option, it is essential to perform periodic backups. Azure Backup stores data in the vault for long-term retention. Choose the GRS option to ensure replication to another Azure region in case of a regional disaster.
For unmanaged disks, you can use LRS, but make sure Azure Backup is enabled with the GRS option in the vault.
Backing up and restoring critical data is complex because these data must be backed up while applications are running. For this, Azure Backup offers application-consistent backups for Microsoft workloads, using the Volume Shadow Service (VSS) to ensure that data is correctly written to storage.
