Last week, Microsoft released preview updates for various versions of Windows before releasing the final builds next patch on Tuesday. Among these was the KB5016691 update for Windows 11 which, although billed primarily as a bugfix update, added new Server Message Block (SMB) compression options.
The same changes were introduced in Windows Server 2022 with update KB5016693, and Microsoft has released details on what these changes mean, as well as how to take advantage of the new options and settings.
With the release of the update previews, Microsoft hasn’t provided much information about the SMB compression changes. At the time, the company simply said, “New! Compress a file regardless of its size if you have configured Server Message Block (SMB) compression”.
In the recently published blog post, however, there is a much more detailed explanation of what has been changed and added.
Microsoft Ned Pyle explains:
There was an idiosyncrasy in the initial design which we changed with the release of Windows Server 2022 update KB5016693 (OS Build 20348.946) and Windows 11 update KB5016691. From now on, if you request compression via SMB, we will try to compress the file regardless of its size or its apparent ability to compress. No matter how you request the compression – robocopy, share setting, registry values - we will try to compress the file.
Microsoft also added a new set of Group Policy, PowerShell, and Registry options to control legacy behaviors that avoid editing the registry by hand to configure client compression. More details are available in the blog post.
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