PolicyPerfMonitorForSDR statement

Use the PolicyPerfMonitorForSDR statement to enable or disable the policy performance monitor function. This function assigns weight fractions to the monitored policy performance data and sends them to the sysplex distributor (SD) distributing stack as the monitored data crosses defined thresholds. The SD distributing stack uses these weight fractions to influence its routing decisions for incoming connection requests toward appropriate hosts within a group responsible for processing the requests. These connection requests are for a specific application (for example, HTTP web) for which one or more policies have been defined. For more information about sysplex distributor policy performance monitoring, see z/OS Communications Server: IP Configuration Guide.

Restriction: This statement applies only when policies are defined for the TCP protocol.

Syntax


>>-PolicyPerfMonitorForSDR--+-Enable--+--| Put Braces and Parameters on Separate Lines |-><
                            '-Disable-'                                                    

Put Braces and Parameters on Separate Lines

|--+-{--------------------------------------+-------------------|
   +-| PolicyPerfMonitorForSDR Parameters |-+   
   '-}--------------------------------------'   

PolicyPerfMonitorForSDR Parameters

   .-SamplingInterval --60-.   
|--+-----------------------+------------------------------------>
   '-SamplingInterval --n--'   

   .-LossRatioAndWeightFr --10 10--.   
>--+-------------------------------+---------------------------->
   '-LossRatioAndWeightFr--+-r f-+-'   
                           '-0---'     

   .-LossMaxWeightFr --100-.   
>--+-----------------------+------------------------------------>
   '-LossMaxWeightFr --n---'   

   .-TimeoutRatioAndWeightFr --10 20--.   
>--+----------------------------------+------------------------->
   '-TimeoutRatioAndWeightFr--+-r f-+-'   
                              '-0---'     

   .-TimeoutMaxWeightFr --100-.   
>--+--------------------------+--------------------------------->
   '-TimeoutMaxWeightFr --n---'   

   .- MaxConnWeightFr --70 85 95-.   
>--+-----------------------------+------------------------------|
   '-MaxConnWeightFr --n n n-----'

Parameters

Enable | Disable

Enables or disables the policy performance monitor function. When active, this function monitors policy performance data on sysplex distributor target stacks and sends information to the Sysplex Distributor distributing stack to be used in balancing the workload among the target stacks. The policy performance data is based on statistics for traffic that maps to defined service policies.

The weight fractions determined for the loss ratio and timeout ratio are added together to form a single weight fraction before being sent to the SD distributing stack. One weight fraction is generated for each DVIPA/port pair on SD target stacks that have at least one policy defined that maps to traffic sent from the target DVIPA/port pair.

SamplingInterval

Specifies the interval in seconds for sampling policy performance data. The default is 60.

LossRatioAndWeightFr

Specifies two numbers. The first is the unit ratio of retransmitted bytes (loss) over transmitted bytes, in tenths of a percent (1 - 1 000). The second number is the weight fraction to be returned to the sysplex distributor distributing stack, in percentage (1 - 100). When present, this parameter results in creation of a threshold table. The first number defines the loss ratio initial threshold value. The second number defines the starting weight fraction that the sysplex distributor distributing stack is to use to reduce the WLM weight for this target stack. For example, if the weight fraction is 50% and the WLM weight is 64, then the resulting weight used for this target stack is 32. The LossMaxWeightFr parameter determines the maximum weight fraction that is reached. The default values for each number is 10. A weight fraction of 0 instructs the system to suppress the loss ratio factor in sysplex distributor computations.

Use the following formula to calculate the threshold table:

if  x(n)% <= % Packet Loss  < x(n+1)%, then weight fraction is y(n)%

x: Initial loss ratio percentage (first number)
y: Initial weight fraction (second number)
n: Integer multiplier

For example, if the first and second numbers are 10 and 10, then the threshold table is:

n=0 : 0% <= % packet loss < 1%; weight fraction is 0%
n=1 : 1% <= % packet loss < 2%; weight fraction is 10%
n=2 : 2% <= % packet loss < 3%; weight fraction is 20%
n=3 : 3% <= % packet loss < 4%; weight fraction is 30%
.
.
.
1(n)%  <= % packet loss < 1(n+1)%; weight fraction is 10(n)%

If the first and second numbers are 30 and 20, then the threshold table is:

n=0: 0% <= % packet loss < 3%; weight fraction is 0%
n=1: 3% <= % packet loss < 6%; weight fraction is 20%
n=2: 6% <= % packet loss < 9%; weight fraction is 40%
n=3: 9% <= % packet loss < 12%; weight fraction is 60%
.
.
.
3(n)%  <= % packet loss < 3(n)%; weight fraction is 20(n)%

Tip: These ratios are not only used as input to create the these weight fractions, but are also used to create the service level fractions. See z/OS Communications Server: IP Configuration Guide for more information about policy based networking.

LossMaxWeightFr

Specifies the maximum weight fraction to be assigned for the loss ratio factor. The default is 100 %.

TimeoutRatioAndWeightFr

Specifies two numbers. The first number is the unit ratio of the number of timeouts over transmitted packets, in tenths of a percent (1 - 1 000). The second number is the weight fraction to be returned to the sysplex distributor distributing stack, in percentage (1 - 100). When present, this parameter results in a creation of a threshold table. The first number defines the timeout ratio initial threshold value. The second number defines the starting weight fraction that the sysplex distributor distributing stack is to use to reduce the WLM weight for this target stack. For example, if the weight fraction is 50% and the WLM weight is 64, the resulting weight used for this target stack is 32. The maximum weight fraction reached is determined by the TimeoutMaxWeightFr parameter. The default values are 10 and 20. A weight fraction of 0 instructs the system to suppress the timeout ratio factor in sysplex distributor computations. See the LossRatioAndWeightFr parameter for more information about how the threshold table is calculated.

TimeoutMaxWeightFr

Specifies the maximum weight fraction to be assigned for the timeout ratio factor. The default is 100%.

MaxConnWeightFr

Specifies three percentages that are used in calculating the connection limit portion of the policy action (service level) weight fractions.

Restriction: Each percentage must be in the range 1 - 100, and each value must be greater than or equal to the preceding value.

The default values are 70, 85, and 95. When calculating the policy action weight fraction, the number of active connections to a target DVIPA/Port is compared with the maximum connections allowed for the associated policy action as follows:

When the number of active connections reaches the percentage of maximum connections specified by the first number, the policy action weight fraction is set to MAX (50%, current calculated value).
When the number of active connections reaches the percentage of maximum connections specified by the second number, the Policy Action weight fraction is set to MAX (85%, current calculated value).
When the number of active connections reaches the percentage of maximum connections specified by the third number, the Policy Action weight fraction is set to 100%.

For more information about how the Policy Agent calculates policy action weight fractions, see z/OS Communications Server: IP Configuration Guide.

Examples

In this example, Policy Agent sends a message to the SD distributing Stack when the loss (retransmission) ratio begins to exceed 1% but not above 2%, with a weight fraction of 20% . This means that the WLM weight is reduced by 20% before it is used as a measure to route incoming connection requests. When the loss (retransmission) ratio exceeds 2%, but not above 3%, a message is sent with a weight fraction of 40%, and so on. When the loss exceeds 5%, a maximum weight fraction of 100% is used. The same is true with the timeout ratio. When the timeout ratio exceeds 0.5%, but not above 1%, a weight fraction of 50% is added to the weight in the message sent to the SD distributing Stack, and so on.

  PolicyPerfMonitorForSDR    Enable
  {
   SamplingInterval             120
      LossRatioAndWeightFr       10    20                         				
      LossMaxWeightFr                 100 
      TimeoutRatioAndWeightFr     5    50                        
      TimeoutMaxWeightFr              100
  }