Microsoft recently rolled out optional updates for its Windows 11 and Windows Server 2022 operating systems. Among the new features included in these updates is the ability to compress files regardless of their size.
Although the release notes do not provide detailed information, Microsoft has revamped the SMB compression website and shared a blog post on the Tech Community website.
With the introduction of Windows 11 and Windows Server 2022, Microsoft incorporated SMB compression capabilities. SMB, short for Server Message Block, is a communication protocol supporting file and printer sharing, as well as network browsing.
SMB compression is designed to reduce the file size during transfers using SMB. Initially, the feature had strict rules in place regarding which files could be compressed.
SMB compression enables users, administrators, or applications to initiate file compression during network transfers. This eliminates the need to manually compress files before transferring, resulting in reduced network bandwidth usage and faster transfers. While this process may slightly increase CPU usage during transfers, it is particularly effective on networks with limited bandwidth, like a client’s 1Gbps ethernet or Wi-Fi network. In contrast, file transfers between servers with flash storage over an uncongested 100Gbps ethernet network might not significantly benefit from SMB compression in practice, but it can alleviate congestion for other applications.
Initially, SMB compression excluded a significant portion of files that could have benefited from compression during transfers.
Microsoft had set a threshold of 100 MiB that required compressibility within the first 500 MiB of a file. This limitation meant that smaller files could not take advantage of the compression feature, leading to potential performance issues during the transfer of large files if the initial segment was not compressible.
The recent update has removed the size restrictions on SMB compression. Now, all files can benefit from compression requests before being transferred.
Microsoft acknowledges that not all files are equally compressible. File types that are already compressed, such as JPG or ZIP, may not derive significant benefits from compression. Conversely, file types like ISO or VHDX often benefit from compression.
Users, administrators, and applications can request compression. Administrators have the option to control this functionality using new policies and PowerShell commands.
Group Policy:
Computer ConfigurationAdministrative TemplatesNetworkLanman Workstation
Disable SMB Compression
Use SMB Compression by Default
Computer ConfigurationAdministrative TemplatesNetworkLanman Server
Disable SMB Compression
Request traffic compression for all shares
PowerShell for SMB client
Set-SMBClientConfiguration [-EnableCompressibilitySampling <bool>] [-CompressibilitySamplingSize <uint64>] [-CompressibleThreshold <uint64>] [-DisableCompression <bool>] [-RequestCompression <bool>]
-DisableCompression $true or $False – never compress even if server or application requested
-RequestCompression $true or $false – always request compression even if server or application didn’t specify it-EnableCompressibilitySampling $true or $false – control legacy sampling behavior
-CompressibilitySamplingSize 1- 9,007,199,254,740,992 – size in bytes of range to sample in a file looking for compressibility
-CompressibleThreshold – 1- 9,007,199,254,740,992 – size in bytes of compressible data that must be found within that range
For further details, refer to the resources provided in the links above.
These updates will be part of the cumulative updates scheduled for September 2022 Patch Tuesday, slated for release on September 13, 2022.
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