1  CALCULATE
   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
 

2  Parameters
 

WINDOW_SIZE

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

2  Qualifiers
 

/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.
 

/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.
 

/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.
 

2  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.