Calculates values you can use with SET commands to control
    OpenVMS Cluster communications. Currently, this command
    calculates the window size that can be used with the SET VC
    /WINDOW=TRANSMIT_SIZE=value and SET VC /WINDOW=RECEIVE_SIZE=value
    commands.

    Parameters for calculating other values might be added in future
    releases.

    Format

      CALCULATE  Parameter

1  –  Parameters

 WINDOW_SIZE

    Calculates a VC window size based on distance and aggregate line
    speed between two nodes.

2  –  Qualifiers

2.1    /SPEED

       /SPEED=linespeed

    Supplies the total speed in Megabits/Sec. of all LAN connections
    between two nodes to be used in calculating the window size.

2.2    /DISTANCE

       /DISTANCE=KILOMETERS [or =MILES]=distance

    Supplies the distance in kilometers or miles of the cable route
    between two nodes to be used in calculating the window size.

2.3    /OPTIMIZE

       /OPTIMIZE=LOCKING [or =IO]=distance

    Supplies the calculation with the type of intersite cluster
    communications to be optimized as follows:

    o  LOCKING indicates that the window size is to be optimized
       for lock messages that are relatively small, or for ICC
       communications using message sizes of up to a few hundred
       bytes.

    o  IO indicates that the window size is to be optimized for MSCP
       served IO, or for ICC communications using large messages.

3  –  Example

  SCACP> CALCULATE WINDOW_SIZE /SPEED=1000/DISTANCE=KILOMETERS=500

      The command in this example calculates the window size to be
      used between two nodes that are 500 kilometers apart, connected
      by a 1Gigabit/Second line speed. The command produces output
      similar to the following:

         Calculate Window Size  2-JUN-2006 17:49:18.41:
                Inter-node link DISTANCE:          500 KILOMETERS
                Inter-node link SPEED:            1000 Mb/s
                ------------------------        ------------------
                Recommended WINDOW SIZE:          1024 frames

      Note that the calculated window size is never smaller than the
      window size PEdriver automatically selects for the VC between
      two nodes, which is based solely on the reported local and
      remote line speeds. However, the calculated value is often
      larger because it includes packets stored in the inter-site
      link and the packet-size mix that the /OPTIMIZE qualifier
      enforces.