Siebel Connection Broker Load Balancing Algorithm

Siebel server architecture supports spawning multiple application object manager processes. The Siebel Connection Broker, SCBroker, tries to balance the load (incoming requests) across different object manager processes running in a single Siebel server.

Least Loaded or Round Robin?

By default, SCBroker forwards the incoming request to any object manager process that is least loaded - meaning the process with the least number of running tasks. In Siebel terminology, this behavior is referred as "least-loaded" or "LL" connection forwarding algorithm. While the default LL algorithm provides the optimal behavior in the best case scenarios, it may lead to serious availability problems if one of several object manager prcesses running in a Siebel server stops responding in a timely fashion [for some reason]. Such an object manager may still accept requests though it may timeout. At some point, the unresponsive/hung or erroneous object manager will have the least number of tasks that may prompt SCBroker component to forward new incoming requests to that object manager process - which in turn leads to a stalemate. To avoid such situations, it is recommended to configure "round-robin" or "RR" algorithm in SCBroker component. When round-robin algorithm is configured, SCBroker ignores the number of running tasks per object manager process and routes all requests to all object managers in a round robin fashion.

While both algorithms have their strengths and weaknesses, customers must weigh both options and choose the one that fits best in their deployment.

eg.,

Find the current load balancing algorithm:

srvrmgr>  list advanced param ConnForwardAlgorithm for comp SCBroker \
             show PA_ALIAS, PA_VALUE, PA_NAME

PA_ALIAS              PA_VALUE  PA_NAME                                    
--------------------  --------  -----------------------------------------  
ConnForwardAlgorithm  LL        Connection Forward algorithm for SCBroker

Configure SCBroker to use round-robin algorithm:

srvrmgr> change param ConnForwardAlgorithm=RR for comp SCBroker server SERVER_NAME
Command completed successfully.

srvrmgr> list advanced param ConnForwardAlgorithm for comp SCBroker \
            show PA_ALIAS, PA_VALUE, PA_NAME

PA_ALIAS              PA_VALUE  PA_NAME                                    
--------------------  --------  -----------------------------------------  
ConnForwardAlgorithm  RR        Connection Forward algorithm for SCBroker

Other SCBroker parameters of interest: ConnForwardTimeout and ConnRequestTimeout

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