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What is the default CIFS TCP window size?

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Applies to

  • ONTAP 9
  • Data ONTAP 7 and earlier

Answer

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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