For more information about SMBv2 and SMBv3 capabilities, see the following articles: The SMBv2 protocol was introduced in Windows Vista and Windows Server 2008, while the SMBv3 protocol was introduced in Windows 8 and Windows Server 2012.

Improved energy efficiency - clients that have open files to a server can sleep.

Large MTU support - for full use of 10 Gigabit Ethernet (GbE).

Client oplock leasing model - limits the data transferred between the client and server, improving performance on high-latency networks and increasing SMB server scalability.

Improved scalability for file sharing - number of users, shares, and open files per server greatly increased.

Improved message signing - HMAC SHA-256 replaces MD5 as hashing algorithm.

Durable handles - allow for connection to transparently reconnect to the server if there's a temporary disconnection.

Caching of folder and file properties - clients keep local copies of folders and files.

Larger reads and writes - better use of faster networks.

Request compounding - allows for sending multiple SMBv2 requests as a single network request.

In Windows 7 and Windows Server 2008 R2, disabling SMBv2 deactivates the following functionality:

Performance Optimizations - optimizations for small random read/write I/O.

Directory Leasing - Improves application response times in branch offices through caching.

Encryption - Provides end-to-end encryption and protects from eavesdropping on untrustworthy networks.

SMB Direct - adds RDMA networking support for high performance, with low latency and low CPU use.

Multichannel - aggregation of network bandwidth and fault tolerance if multiple paths are available between client and server.

Scale Out - concurrent access to shared data on all file cluster nodes.

Transparent Failover - clients reconnect without interruption to cluster nodes during maintenance or failover.

In Windows 10, Windows 8.1, Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, and Windows Server 2012, disabling SMBv3 deactivates the following functionality: For more information, see How to detect status, enable, and disable SMB protocols on the SMB Server. We recommend keeping SMBv2 and SMBv3 enabled, but you might find it useful to disable one temporarily for troubleshooting.

Disabling SMBv2 or SMBv3 for troubleshooting While disabling or removing SMBv1 might cause some compatibility issues with old computers or software, SMBv1 has significant security vulnerabilities and we strongly encourage you not to use it. This article describes how to enable and disable Server Message Block (SMB) version 1 (SMBv1), SMB version 2 (SMBv2), and SMB version 3 (SMBv3) on the SMB client and server components. Applies to: Windows Server 2022, Windows 10, Windows 8.1, Windows 8, Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, Windows Server 2012

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