SMB3 PowerShell changes in Windows Server 2012 R2: SMB Multi-instance


Windows Server 2012 R2 introduced a new version of SMB. Technically it’s SMB version 3.02, but we continue to call it just SMB3. The main changes are described at

With this new release, we made a few changes in SMB PowerShell to support the new scenarios and features. This includes a few new cmdlets and some changes to existing cmdlets, with extra care not break any of your existing scripts.

This blog post outlines one of the 7 set of changes related to SMB PowerShell in Windows Server 2012 R2.


SMB Multi-instance


SMB Multi-instance is a new feature in Windows Server 2012 R2 that separates regular SMB traffic from CSV-related inter-node SMB traffic in distinct  SMB instances.

This is designed to improve isolation between the two types of traffic in improve the reliability of the SMB servers.

Information related to this new CSV-only instance in Windows Server 2012 R2 is typically hidden by default in all PowerShell cmdlets.


Showing hidden instance information


There are the changes in SMB PowerShell so an Administrator can view information related to the hidden CSV instance:

  • The "-SmbInstance CSV" option in Get-SmbConnection and Get-SmbMultichannelConnection will show the connections associated with the hidden CSV instance.

  • There is now an InstanceName property in the full output of Get-SmbConnection, Get-SmbMultichannelConnection, Get-SmbSession and Get-SmbOpenFile. It shows either “Default” or “CSV” (only shows if using the –SmbInstance option).


There is really little use in inspecting the information on the hidden CSV instance, except if you’re troubleshooting CSV inter-node communications.




This blog post is an updated version of the September 2013 post at focused on a single topic.

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