For large-scale, high-available deployment of Sun Suite of Products (e.g. Sun Portal Server, Sun Access Manager and Sun Directory Server), there is always a need for a hardware load-balancer to sit in-front of each set of components.
The diagram below illustrates a complicated setup of Sun Portal Solution with Secured Remote Access (SRA):
e.g. HA SRA, HA Portal, HA Access Manager, HA Directory Server
If you have such a setup, a properly configured health-check on the load-balancer is required.
Load balancers use a health-check mechanism to establish if a service instance is properly working and if it can process requests from clients. If the health-checks succeed, the load balancer includes the service instance in the pool of available instances, and requests are routed to the instance based on the existing scheduling rules. However, if the health-checks fail, the instance is removed from the load balancer's scheduling list.
Do take note of the following, in particular:
1. Health-check Timeout
2. Interval Between Checks
3. Consecutive Failed Health-check Threshold
PS: The above figures can be used for other large-scale deployment that uses HA Directory Server or HA Access Manager/OpenSSO Server.