title	Install the Microsoft Azure Recovery Services (MARS) agent
description	Learn how to install the Microsoft Azure Recovery Services (MARS) agent to back up Windows machines.
ms.topic	how-to
ms.date	08/06/2025
ms.service	azure-backup
author	AbhishekMallick-MS
ms.author	v-mallicka

Install the Azure Backup MARS agent

This article describes how to install the Microsoft Azure Recovery Services (MARS) agent. MARS is also known as the Azure Backup agent.

About the MARS agent

Azure Backup uses the MARS agent to back up files, folders, and system state from on-premises machines and Azure VMs. Those backups are stored in a Recovery Services vault in Azure. You can run the agent:

Directly on on-premises Windows machines. These machines can back up directly to a Recovery Services vault in Azure.
On Azure VMs that run Windows side by side with the Azure VM backup extension. The agent backs up specific files and folders on the VM.
On a Microsoft Azure Backup Server (MABS) instance or a System Center Data Protection Manager (DPM) server. In this scenario, machines and workloads back up to MABS or Data Protection Manager. Then MABS or Data Protection Manager uses the MARS agent to back up to a vault in Azure.

The data that's available for backup depends on where the agent is installed.

Note

Generally, you back up an Azure VM by using an Azure Backup extension on the VM. This method backs up the entire VM. If you want to back up specific files and folders on the VM, install and use the MARS agent alongside the extension. For more information, see Architecture of a built-in Azure VM backup.

Before you start

Before you install the MARS agent, ensure that you have performed the following actions:

Learn how Azure Backup uses the MARS agent to back up Windows machines.
Learn about the backup architecture that runs the MARS agent on a secondary MABS or Data Protection Manager server.
Review what's supported and what you can back up by the MARS agent.
Make sure that you have an Azure account if you need to back up a server or client to Azure. If you don't have an account, you can create a free one in just a few minutes.
Verify internet access on the machines that you want to back up.
Ensure the user installing and configuring the MARS agent has local administrator privileges on the server to be protected.
Ensure your server is running on TLS 1.2.
To prevent errors during vault registration, ensure that the latest MARS agent version is used. If not, we recommend you to download it from here or from the Azure portal as mentioned in this section.

[!INCLUDE How to create a Recovery Services vault]

Modify storage replication

By default, vaults use geo-redundant storage (GRS).

If the vault is your primary backup mechanism, we recommend that you use GRS.
You can use locally redundant storage (LRS) to reduce Azure storage costs.

To modify the storage replication type, follow these steps:

In the new vault, select Properties under the Settings section.
On the Properties page, under Backup Configuration, select Update.
Select the storage replication type, and select Save.

Note

You can't modify the storage replication type after the vault is set up and contains backup items. If you want to do this, you need to re-create the vault.

Configure Recovery Services vault to save passphrase to Azure Key Vault

Azure Backup using the Recovery Services agent (MARS) allows you to back up file or folder and system state data to Azure Recovery Services vault. This data is encrypted using a passphrase provided during the installation and registration of the MARS agent. This passphrase is required to retrieve and restore the backup data and needs to be saved in a secure external location, such as Key Vault.

We recommend you create a key vault and provide permissions to your Recovery Services vault to save the passphrase to the key vault. Learn more.

Verify internet access

[!INCLUDE Configuring network connectivity]

Download the MARS agent

Download the MARS agent so that you can install it on the machines that you want to back up.

If you've already installed the agent on any machines, ensure you're running the latest agent version. Find the latest version in the portal, or download from here.

In the vault, under Getting Started, select Backup.
Under Where is your workload running?, select On-premises. Select this option even if you want to install the MARS agent on an Azure VM.
Under What do you want to back up?, select Files and folders. You can also select System State. Many other options are available, but these options are supported only if you're running a secondary backup server. Select Prepare Infrastructure.
For Prepare infrastructure, under Install Recovery Services agent, download the MARS agent.
In the download menu, select Save. By default, the MARSagentinstaller.exe file is saved to your Downloads folder.
Select Already download or using the latest Recovery Services Agent, and then download the vault credentials.
Select Save. The file is downloaded to your Downloads folder. You can't open the vault credentials file.

Install and register the agent

To install and register the MARRS agent, follow these steps:

Run the MARSagentinstaller.exe file on the machines that you want to back up.

[!Note] If you haven't selected the option Give me updates for other Microsoft products when I update Windows in OS settings, the following setting screen might appear. However, the automatic updates of MARS on Microsoft updates aren't currently implemented.

:::image type="content" source="./media/backup-configure-vault/setting-page.png" alt-text="Screenshot shows the settings page for MARS.":::
In the MARS Agent Setup Wizard, select Installation Settings. There, choose where to install the agent, and choose a location for the cache. Then select Next.
- Azure Backup uses the cache to store data snapshots before sending them to Azure.
- The cache location should have free space equal to at least 5 percent of the size of the data you'll back up.
For Proxy Configuration, specify how the agent that runs on the Windows machine will connect to the internet. Then select Next.
- If you use a custom proxy, specify any necessary proxy settings and credentials.
- Remember that the agent needs access to specific URLs.
For Installation, review the prerequisites, and select Install.

[!Note] MARS agent installation requires Windows Powershell 5.0 and Microsoft .NET Framework 4.8 (previously 4.5). You might need to install the .NET Framework 4.8 manually when upgrading from version 4.5.
After the agent is installed, select Proceed to Registration.
In Register Server Wizard > Vault Identification, browse to and select the credentials file that you downloaded. Then select Next.
On the Encryption Setting page, specify a passphrase that will be used to encrypt and decrypt backups for the machine. Learn more about the allowed passphrase characters.
- Save the passphrase in a secure location. You need it to restore a backup.
- If you lose or forget the passphrase, Microsoft can't help you recover the backup data.
The MARS agent can automatically save the passphrase securely to Azure Key Vault. So, we recommend you create a Key Vault and grant permissions to your Recovery Services vault to save the passphrase to the Key Vault before registering your first MARS agent to the vault. Learn more.

After granting the required permissions, you can save the passphrase to the Key Vault by copying the Key Vault URI from the Azure portal and to the Register Server Wizard.

:::image type="content" source="./media/backup-configure-vault/encryption-settings-passphrase-to-encrypt-decrypt-backups.png" alt-text="Screenshot shows how to specify a passphrase to be used to encrypt and decrypt backups for machines.":::
Select Finish. The agent is now installed, and your machine is registered to the vault. You're ready to configure and schedule your backup.

If you are running into issues during vault registration, see the troubleshooting guide.

[!Note] We recommend to save your passphrase in an alternate secure location, such as Azure Key Vault. Microsoft can't recover the data without the passphrase. Learn how to store a secret in Key Vault.