Load balancing refers to the practice of distributing a workload over multiple resources. Its specific application in an Oracle environment is with respect to Oracle Parallel Server. When OPS is used, you have multiple instances running on multiple nodes all accessing the same physical database. This situation is illustrated in Figure 8.7.
Figure 8-7. A load-balanced OPS environment
This figure illustrates an environment where the client connections have been distributed evenly among the various nodes. Assuming that each client represents a similar amount of work, this even distribution is ideal. You don’t want to have one machine sitting idle while another is overloaded.
Client Load Balancing
Load balancing can be done at either the client or the server level. Net8 supports client load balancing, which is achieved by giving each client a list of possible nodes for a given Net8 connection. When the client attempts a connection, the Net8 software on the client randomly chooses from that list.
Client node balancing is configured at the net service name level. It is similar to a failover configuration in that it makes use of multiple addresses in an address list, or of multiple descriptions in a description list. The major difference is that when load balancing is done, Net8 tries addresses or descriptions in random order rather than in sequential order.
When client load balancing ...