Oracle database clustering

If you use an Oracle database system to host the metadata repository database or the IBM® InfoSphere® Information Analyzer analysis database, you can increase the availability of the metadata repository tier by implementing Oracle Real Application Clusters (RAC).

An Oracle RAC configuration consists of multiple computers, each of which runs an Oracle instance, which is made up of processes that provide access to stored data. Each Oracle instance has access to a common database file system across a high-speed network. If a computer or Oracle instance process fails, other Oracle instances continue to provide service. Oracle database cluster management software (Oracle Clusterware) monitors and manages the Oracle RAC configuration and tries to restart failed Oracle instances.

Client processes access the Oracle RAC configuration in the same way that they access a single Oracle database instance. With Oracle RAC 11g, a virtual IP address is assigned to each server in the cluster. If a node in the cluster fails, the virtual IP address fails over to another node and client processes can automatically reconnect.

Nodes in an Oracle RAC cluster require a separate, private high-speed network for messaging between nodes. This network is called the interconnect.

The following figure shows an IBM InfoSphere Information Server topology that includes Oracle RAC. The two Oracle RAC node computers share access to a database farm.

Figure 1. Topology with Oracle RAC configuration
This figure shows a topology that includes a metadata repository tier where Oracle Real Application Clusters (RAC) is implemented across two computers. In the figure, dotted lines show communication between computers. At the top of the figure, there are three client workstation computers labeled "client tier". HTTP clients within the workstations communicate with the load balancer. The load balancer communicates with two web servers. A backup load balancer communicates with the load balancer. Below these components is a line that indicates the firewall. The web servers each communicate through the firewall with two application server nodes. These nodes are grouped in a cluster. EJB clients within the client workstations communicate with the application server nodes. A separate Deployment Manager computer also communicates with the application server nodes. The nodes and the Deployment Manager computer make up the services tier. In the lower left corner there are two computers that share a storage area network (SAN). These components make up the engine tier. One of the computers is labeled "active," and the other is labeled "passive." Each computer is running HA cluster management software. There is a heartbeat between the two computers. Each node in the services tier communicates with the "active" computer. In the lower right corner, two computers are labeled "metadata repository computer." An RAC cluster is shown implement across the computers. The cluster communicates with a group of databases labeled "database farm." The application servers each communicate with both metadata repository computers.

If a node in the RAC cluster fails, other nodes continue to provide service.

For greater high availability, you can implement an Oracle RAC on Extended Distance Clusters configuration. In this configuration, nodes in the cluster are located in physically separated sites.

To install InfoSphere Information Server in an Oracle RAC configuration, install to a single node in the configuration. Then perform additional steps to cause InfoSphere Information Server to operate with the complete Oracle RAC configuration.