Oracle Real Application Clusters (Oracle RAC) provides a high availability and scalable database solution. All Oracle Real Application Clusters have certain things in common, each cluster has Oracle Grid Infrastructure installed locally on each server. Oracle Grid Infrastructure also includes Oracle Automatic Storage Management (Oracle ASM) and Oracle Clusterware.
Each Instance in the Oracle RAC accesses the database files stored on shared storage. Each node also runs its own operating system and requires local storage, which is used to store Oracle Grid Infrastructure and Oracle AI Database software. In an Oracle RAC environment, while most files like data files, control files, and generally redo log files are shared across all instances to ensure consistency and availability, certain files can be local to each instance. These files include local temporary files, trace files, instance-specific redo logs, dump files, and optionally the password files.
Each node needs at least one public network for client connections and a private network for inter-node communication. Each network may use multiple network interface cards (NICs) to increase bandwidth, availability, and fault tolerance. Oracle recommends that each network use multiple network interface cards per node and multiple network switches in each network to avoid a single point of failure. The Oracle RAC option with Oracle AI Database enables you to cluster database instances. Oracle RAC uses Oracle Clusterware for the infrastructure to bind multiple servers so they operate as a single system.
Oracle Clusterware is the only clusterware that you need for most platforms on which Oracle RAC operates.