SIRIS, ALTO, and NAS: Datto Windows Agent: Excluding the DFS writer for VSS backups



This article describes the procedure to exclude the DFS Replication Service VSS writer from being used in Datto Windows Agent backups due to performance issues in some scenarios.


  • Datto Windows Agent version 2.2 and newer
  • Microsoft Windows 2016
  • Microsoft Windows 2019


The procedures outlined below should only be necessary on Windows Server 2016, and 2019 systems that have DFS replication enabled and are having performance issues, such as Windows Explorer crashing while running backups with Datto Windows Agent version 2.2 or newer. The first step to resolving this issue should always be to update to the latest version of the Datto Windows Agent, as the most recent versions of the agent software have several improvements designed to lessen the likelihood of this issue occurring. You can download the most recent DWA version at

If, after you've updated to the newest DWA version, you continue to experience the problem, there are two potential workarounds that could be applied.

 Exclude the DFS writer from backups

Excluding the DFS writer will cause a crash-consistent backup of the DFS database on the server. This risk is mitigated by the existence of DFS DB replicas on other servers in the replication group that it can reconcile with.

Datto has not observed backup issues resulting from the exclusion of the DFS writer. Contact Microsoft for support if you have any questions about how excluding this VSS writer may impact your environment.

To exclude the DFS Replication Service VSS writer from future backups, follow the steps below.

  1. Open the GUI for the Datto appliance.
  2. Click the Protect tab.
  3. Find the agent you wish to configure and click Configure Agent Settings.
  4. Scroll down to the Advanced section to the VSS writer exclusion settings.
  5. Disable the DFS Replication Service VSS writer.

Disable DFSR replication for scheduled backup periods 

While a more advanced solution to implement, it is possible to create a script using Microsoft PowerShell, which establishes a schedule allowing for DFS Replication Services to be disabled during backup times. See the Microsoft article  Set-Dfsr Group Schedule (external link) for information on creating a schedule. Separating DFSR schedule and Datto Backup schedule will result in less frequent backups jobs.

If backup performance issues persist after making these changes, collect the memory dump files as outlined in Datto Windows Agent: How to retrieve memory dump files and contact Datto Technical Support

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