Programming Guides › Programming Guide for Perl › Policy Management Operations › Manage Policy Server Load Distribution

Manage Policy Server Load Distribution

To help prevent service interruptions, SiteMinder includes a failover feature. If the primary Policy Server fails and failover is enabled, a backup Policy Server takes over policy operations. Beginning with SiteMinder v6.0, failover can occur not only between Policy Servers, but between groups, or clusters, of Policy Servers.

The cluster functionality also improves server performance by providing dynamic load balancing between the servers in a cluster. With dynamic load balancing, policy operations are automatically distributed between the available servers in a cluster according to the performance capabilities of each server.

A host configuration can be associated with one or more Policy Servers, or with one or more clusters of Policy Servers, depending on how you define your host configuration object:

• Clustered servers
  • Call AddCluster() for each cluster to create in the host configuration.
  • In the PolicyMgtCluster object returned from AddCluster(), call AddServer() to populate the cluster with servers.

  Behavior: Failover occurs between clusters of servers if multiple clusters are defined. Also, requests to servers within a cluster are sent according to the improved performance-based load-balancing techniques introduced with Agent API v6.0.

• Non-clustered servers
  • Call AddServer() for each non-clustered server to create in the host configuration.

  Behavior: Behavior is the same as in v5.x installations—that is, you can enable failover among the servers associated with a host configuration (set EnableFailover() to 1), or you can enable round-robin behavior among the servers (set EnableFailover() to 0).

  When round-robin behavior is enabled, the improved performance-based load-balancing techniques introduced with Agent API are used.

Note: You cannot mix clustered and non-clustered servers in a host configuration.