Getting Started with the Datto Windows Agent



This article describes the steps to install the Datto Windows Agent, as well as steps for troubleshooting installation issues.

Do not install the Datto Windows Agent on any system currently protected by the ShadowSnap agent, even if the ShadowSnap agent is no longer installed. Installing the Datto Windows Agent will start a new backup chain for the protected system and will not continue your existing ShadowSnap chain.


  • Datto Windows Agent


[VIDEO] One Take: A Look at the Datto Windows Agent

Pre-Deployment Requirements

  • Before installing the Datto Windows Agent, verify that no other backup software is installed on the production machine, and that any VSS providers left behind by the prior installation of backup software are not present. Ensure that the target machine is in good health. It is extremely important to run a virus scan, disk defragmentation, and a disk health check (chkdsk /r) before installation.
  • Datto recommends reviewing the Encryption Compatibility With The Datto Solution Knowledge Base article when deploying the agent to encrypted machines.
  • Connectivity of the protected machine to the Internet is required when installing the Datto Windows Agent, and during initial agent pairing.
  • New versions of the Datto Windows Agent require the device to run Datto OS software v.3.68.8 or higher.

Requirements for your target server and your network:

    • Gigabit connections from the Datto to all relevant network infrastructure (Check switch ports, try to have the Datto appliance on a gigabit switch whenever possible)
    • Supported operating systems: 
      • Windows XP Service Pack 3
      • Windows Server 2003 Service Pack 2
      • Windows Server 2008 Service Pack 2
      • Windows 7 Service Pack 1
      • Windows Server 2008 R2 Service Pack 1 and later
Compatibility of this backup solution with any hypervisor environment or operating system not listed in this article is untested, and may yield unreliable results.
  • At least 10% of the volume must be free at time of install, so we may create a file in the root of the volume to handle block transport during transfers. This is a common requirement among backup agents so that the agent has sufficient space to track and block-transfer changes for subsequent backups.
    • The Datto Windows Agent requires 10% free space (up to 10 GB) per volume, with the exception of volumes over 1TB, which will use 1% of the total free disk space.
    • In both sizing scenarios, an additional 2 GB of free space for operational overhead is required.

  • At least 1GB of RAM must remain free during normal operations of the production machine for install and backups to run
  • NTFS filesystems (ReFS is not currently supported)
    • The Datto solution is capable of backing up multiple types of disk sector schemes. The process writes an image-based backup to a file which is 512 bytes per physical sector. While rare, certain software which relies on advanced formats, such as 4K, may have issues with the sector size change. Datto recommends performing regular DR tests to ensure that all required applications function as expected in our virtualized environments.
    • The Datto Windows Agent can only back up volumes that are recognized by the Windows operating system as local, stable volumes. It cannot back up mapped network drives, iSCSI targets, or removable drives.
  • Firewall rules:
    • The protected machine must have Internet access, and be able to reach, for the initial installation of the Datto Windows Agent.
    • Ensure connectivity is available through all active firewalls from the protected machine to the Datto appliance on the following ports:
      • Port 3260 (for iSCSI), 3262 (for Mercury), UDP 139, and TCP 25568.
      • From the Datto appliance to the protected machine: TCP port 25568.
        • The Datto Windows Agent uses Mercury as its primary transport method; however, if this fails, backups are intended to fall back to iSCSI.
    • From Datto appliance to internet: ports 22, 80, 123, 443 outbound to at minimum the addresses specified in this article: Datto IP Ranges.
  • You may need additional addresses for the continuity of off-site syncing. See Datto Networking Requirements for local and offsite networking requirements and best practices for Datto appliances.
  • Antivirus exceptions:
    • Set service-level exceptions for the Datto Backup Agent and Datto Provider services. 
    • Set an application-level exception for the Datto Windows agent (DattoBackupAgent.exe).
    • Whitelist the following installation path: %PROGRAMFILES%\Datto\Datto Windows Agent\
  • Datto does not endorse or support backing up laptops with the Datto Windows Agent due to their mobile nature; laptops must be inside the LAN and not on a wireless network to perform backups in a timely manner. Attempts to do so are at your own discretion.

Figure 1 illustrates the data flow for the Datto Windows Agent solution.

Figure 1: Datto Windows Agent logical data flow (click for larger image)


After you have checked the server, go to and click the Windows button under Backup Agent Download. You must have internet access during the install and the initial start so that the agent can retrieve certificates. Once you have installed the agent, you may pair the agent to the Datto device and begin configurations.

Note that if your machine will not have regular internet access, you will have to manually check for updates to upgrade to newer versions.

However, you must reboot the system before you can load the backup driver, which is necessary to begin running backups.

When you install the Datto Windows Agent, it creates a DattoCTRL file and a DattoSNAP file on the protected server, in the root directory of each protected volume. You may need to select the Show hidden files and folders in Windows to see them.

DattoCTRL is created at the start of the first backup, and contains the space for the Copy On Write (COW) information during the backup.

  • If a volume is selected for backup, 10% of the volume free space is required on that volume for the DattoCTRL file (up to 10 GB).
    • However, if the volume is large enough that 10 GB represents less than 10% of the total disk space, the percentage of the disk that represents 10 GB is required.
  • If the 10% number is larger than 10 GB, the file's size will be set at 1% of the total size of the protected volume.

To calculate the amount of space needed on your protected machine on a per-volume basis, use the size of the target volume and refer to the scenario matching your production environment. Refer to the Datto Windows Agent's storage space requirements for more information.

DattoSNAP is the file that the Datto Windows Agent writes the changed block information to, so that it knows what it need to move during each backup.

Setting Schedules / Initial Configurations

Items to consider when configuring the Datto Windows Agent:

  • Before setting a backup schedule, discuss with your client how far back you would ever need to go to retrieve data. Set the expectations with them and provide a schedule accordingly. Set the local data retention policies based on these conversations and expectations. Remember that long-running retention policies will require more disk space, and should be considered when sizing an appliance.
  • Consider the server’s application: while a file server may need to be backed up during business hours as files are in constant change, a terminal server that simply houses configurations may not require as many backups per day as there is little to no change provided. Backups are just like any other service on a server, they consume resources and take disk input / output. Consider this while setting a schedule.
  • The size of your server's backups can grow if you use Distributed File System (DFS) in your environment. See How Distributed File System (DFS) Interacts with the Datto Solution for more information.
  • Before you take the first backup, make sure that any volumes that you do not want to be backed up are excluded from the advanced options tab. Remember that any additional drive that is attached to the machine may attempt to be backed up (USB drive, additional storage drive, etc.)
For information on other Datto backup configurations, see Configuring Alerts and SpeedSync.

Verify Installation

The Datto Windows Agent does not have a GUI. Follow these steps to verify that the installation was successful:

  1. Make sure the production machine has been rebooted following the installation of the Datto Windows Agent.
  2. Check Programs and Features to ensure that Datto Windows Agent is listed as an installed program.
  3. Make sure that both essential services are present Datto Backup Agent Service and DattoProvider
  4. Attempt to pair the protected system via the web UI of your Datto appliance, and start a backup for it. Both processes should complete successfully.

Software Updates

The Datto Windows Agent automatically updates itself when a new version becomes available, except when the release includes a driver update. Because a driver update requires an update of the host system, you will need to download and install these versions manually. You can download the latest releases of the Datto Windows Agent at the Datto Download Page.

The current version of the Datto Windows Agent is 1.1.0. You can check the protected machine's agent version from the Protect tab of your Datto appliance's GUI.


Best-Practices for Troubleshooting Installation Errors

  • If you get an error during DWA installation, check the Windows Event Logs for any corresponding events.
  • If Visual C++ 2015 runtime is not up to date/not installed properly this could prevent an install.
  • If the GUI install fails, run the following from an administrator command prompt (if installed to a non-default location, replace the install location below)
    "C:\Program Files\Datto\Datto Windows Agent\DattoBackupAgent.exe" -install'
  • If you see errors related to VC runtime, reinstall the latest Visual C++ update.

Install of the Datto Agent Service Failed. Uninstall and run the install again

Windows Server 2012r2
This error message can be caused by missing Windows updates. To resolve this error, make sure that the following Windows updates are installed on the protected system:

1. KB2919422
2. Clearcompressionflag.exe
3. KB2919355
4. KB2932046
5. KB2959977
6. KB2937592
7. KB2938439
8. KB2934018
9. Visual C++ Redistributable for Visual Studio 2015

After installing any missing updates, re-run the Datto Windows Agent installer.

Install of the Datto Provider Failed. Uninstall and run the install again.

This error message can be caused if the Distributed Transaction Coordinator service is in an unusable state. To troubleshoot this issue:

1. Check the Windows Event Logs for the Complus error shown in Figure 2.

Figure 2: Complus failure (click for larger image)

2. Using the Services control panel (services.msc), make sure that the Distributed Transaction Coordinator service is running. If it is not running, start it. If it is running, restart it.

Figure 3: Distributed Transaction Coordinator (click for larger image)

Additional Resources

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