Oracle introduced Real Application Cluster (RAC) with Oracle9i, and RAC is also a key feature of Oracle 10g. Oracle RAC allows a single physical Oracle database to be accessed by concurrent instances of Oracle running across several different CPUs.
An Oracle RAC is composed of a group of independent servers, or nodes, that cooperate as a single system. A cluster architecture such as this provides applications access to more computing power when needed, while allowing computing resources to be used for other applications when database resources are not as heavily required. For example, in the event of a sudden increase in network traffic, an Oracle RAC can distribute the load over many nodes, a feature referred to as server load balancing. Oracle RAC features are available to you simply by connecting to an Oracle RAC system with the Oracle driver. There is no additional configuration required.
Failover and client load balancing can be used with an Oracle RAC system, but they are not specifically part of Oracle RAC. These features also can be used with any other database supported by the DataDirect Connect Series forJDBC. See "Using failover" and "Using client load balancing" for an overview.
See "Configuring failover" for information about using failover with Oracle databases. See "Using tnsnames.ora files" for information about configuring failover and client load balancing using a tnsnames.ora file.
