Saturation Load Balancing

With the saturation load balancing algorithm, the Sun OpenDS Standard Edition proxy sends requests to a chosen priority route. The Sun OpenDS Standard Edition proxy continues to send requests to the priority route until the back-end LDAP server on that route passes the saturation threshold set. The saturation threshold is represented as a percentage.

For example, if you want a back-end LDAP server to manage all incoming requests, set it as priority 1. If you want that same back-end LDAP server to stop handling requests when its saturation index reaches 70%, set the saturation threshold to 70%, as illustrated in Figure 4-6. In this way, the server handles all incoming requests until it becomes 70% saturated. The Sun OpenDS Standard Edition proxy then sends all new requests to the back-end LDAP server to Server 2, since it has the next highest priority. Server 2 will continue to handle requests until it reaches its own saturation threshold, or until Server 1 is no longer saturated.

In other words, if Server 1 reaches 70% saturation, Sun OpenDS Standard Edition proxy directs the requests to Server 2. If Server 1 is still at 70%, and Server 2 reaches 60%, then Sun OpenDS Standard Edition proxy directs the new requests to Server 3.

However, if while Server 2 is handling requests, the saturation level of Server 1 drops to 55%, thenSun OpenDS Standard Edition proxy will direct all new requests to Server 1, even if Server 2 has not reached its saturation threshold.

Figure 4-6

Saturation Load Balancing Example

If all routes have reached their saturation threshold, the Sun OpenDS Standard Edition proxy chooses the route with the lowest saturation.

With the Sun OpenDS Standard Edition proxy, you can set a saturation threshold alert. For example, if you set a saturation threshold alert to 60%, you will get a notification when the server reaches this limit, and thus, you can act before the server becomes too degraded.