What’s New in Azure File Sync? – November 2018 Edition

Improvements are coming quickly to Azure File Sync (AFS), a new hybrid service that has server admins very interested. This post will discuss some of the new features that were introduced with v4 of the AFS agent.

Rapid Improvement

I frequently remind people not to judge an Azure service by its first generally available (GA) release. The developers of Microsoft Azure code in sprint runs. Development cycles last 6 months and planning is done every 3 months. Within those overlapping cycles, the teams can change direction quite quickly and produce new features in a matter of weeks, instead of years.

Azure File Sync was not perfect when it was released – and the team knew that. They already had years of feedback from private and public tests and had built plans. Adoption came with GA, and that brought more feedback and empirical data based on real-world usage. Better informed, the team can now improve the product in ways that will be meaningful to current and potential customers.

V4 Improvements

Version 4 of the AFS agent was released in November. This new agent version comes with many improvements:

  • Windows Server 2019: WS2019 might still be lacking a lot of hardware support, but AFS now supports an installation of the v4 agent on the new server OS version. Now the supported file server operating systems are Windows Server 2019, Windows Server 2016, and Windows Server 2012 R2.
  • Date-based tiering policy: I had quite a few people ask for this – the ability to “pin” files to the hot cache of the file server based on the last access date instead of “temperature”.
  • New server improvement: When adding a new server to a sync group, files are downloaded based on the recently created/modified date from the other servers in the sync group.
  • Anti-Virus: Tiered files can use the FILE_ATTRIBUTE_RECALL_ON_DATA_ACCESS attribute to improve anti-virus and other systems that would otherwise wastefully download cold files from the cloud.
  • Unattended Installations: An answer file can be used for unattended installations of the agent.
  • Volume restore option: You can restore a volume on servers that do not have tiering enabled.
  • Improved Sync: It supports bidirectional control characters.
  • Performance: A number of performance and reliability improvements were made to synchronization and cloud tiering.


Some issues were also fixed in AFS:

  • Slow tiering: An issue where it can take up to 24 hours to tier files was fixed.
  • Application proxy: Some agents had issues communicating with the cloud if this option was enabled – this is fixed.
  • Deleting a server endpoint: An issue was fixed when a server endpoint was deleted, and the tiered files became unusable without a workaround.


If you have a previous installation of the agent, then it must be version or later to update to v (the new version). You can manually download the agent, but Windows Update will update the agent if you have included it in any centrally managed system, such as WSUS.