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NetApp Knowledge Base

What is the default CIFS TCP window size?

Last Updated:

Applies to

  • ONTAP 9
  • Data ONTAP 7 and earlier


The default CIFS TCP window size on the controller is 17520 bytes, but can be increased to 8387700 bytes. To view the current setting, run the following command:

Filer> options cifs.tcp_window_size

For more information on how to force the Windows 2000/XP client to use larger window sizes, refer to CIFS TCP Window size is limited to 64240 bytes.

Note: CIFS should be terminated and restarted for the option cifs.tcp_window_size to take effect. The TCP window size is only set when CIFS registers with the network code. That happens when CIFS starts or when a new name is registered as a NetBIOS alias. If you are not restarting CIFS, only the newly registered names will have the changed window size. When registering a NetBIOS alias, CIFS looks at the controller's registry key options.cifsinternal.aliaswindowsize to get the value to use. This value is updated whenever a NetBIOS alias is created and it uses the then-current value of cifs.tcp_window_size. This registry value is maintained separately from the current value of cifs.tcp_window_size.

For additional information, refer the performance section of your respective Data ONTAP System Administrator's Guide.

Related Link

Note: In ONTAP 9, the maximum TCP window receive size has been pre-set to 7631441 bytes.

Additional Information

TCP Window Size in ONTAP


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