There are four load distribution policies:
Random – static, even distribution.
Round-robin – static, even distribution.
Weighted – static, random based on server weight.
Adaptive – dynamic, random based on load metrics.
The first three policies do not rely on load metrics, so there is no need to obtain an NLL.
The naming service applies the selected load distribution policy and generates an IOR with multiple profiles. See “Interoperable object references” for more information.
Both random and round-robin policies attempt to evenly distribute incoming client requests to all participating servers. These distribution policies are ideal for a cluster with comparable physical nodes that have similar performance characteristics.
The weighted policy allows you to specify the processing load to each server. This policy is designed for physical nodes with a wide range of performance variations. You can specify any weight between 1and 5 for each server. A larger number indicates that the server can handle a larger load.
The adaptive policy is similar to the weighted policy but adapts for runtime load variation. It examines the NLL for current load metrics, and compensates for uneven loads by distributing proportionately more client requests to lightly loaded servers. There is more overhead with the adaptive policy than the other policies.
Load collectors reside in each server, and the failure of any load collector has no global effect. If a broadcast of load metrics from a particular load collector has not been received for a predefined period of time, the corresponding server is dropped from the NLL.The load distribution is fully synchronized and is linked to the name servers as part of the naming services. The high availability protection for naming services also applies to dynamic load balancing. See “Understanding high availability” for more information.
