Implementation Guide › Performance Tuning › Web Tier Performance › Improve Web Agent Performance through Load Balancing › Failover and Load Balancing with Multi-Threaded Web Servers

Failover and Load Balancing with Multi-Threaded Web Servers

Web Agents running on multi-threaded web servers (such as Sun Java System, IIS, or an Apache-based server in worker mode), open the minimum number of sockets to a Policy Server at startup.

If you configure your environment for failover or load-balancing between Policy Servers, then the Web Agent opens the minimum number of sockets to each Policy Server at startup. Connections to a load-balanced Policy Server occur in the same way, although fewer sockets are opened to each Policy Server, because each is getting only half of the total requests.

If configured for failover, and an error occurs between the Web Agent and the primary Policy Server, then connections to the failover Policy Server are used. Failover occurs per service, so there could be active connections to both the primary and the failover Policy Servers at once. Once the primary Policy Server comes back up, the sockets opened to the failover server remain. All new sockets are opened to the primary Policy Server.