In an Oracle Real Application Clusters (Oracle RAC) environment, database files are stored and managed across multiple cluster nodes. Every instance can access the data files, including the data files associated with Undo tablespaces and control files. Each Instance has an Undo Tablespace dedicated to it that is stored on the shared storage. All redo log files are accessible to all instances, each redo log file is multiplexed as in a single instance. When using Oracle ASM with normal redundancy each redo log member is mirrored, and a second Multiplexed member is placed in a different disk group. Each instance has at least two redo log groups also called a thread. The Oracle RAC database files include:

A common (default) SPFILE with both the common parameters and instance specific parameters is highly recommended in shared storage. The SPFILE can be stored in Oracle ASM. Some initialization parameters are the same across all instances in a cluster, and some are unique per instance.

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 include local temporary files, trace files, instance-specific redo logs, dump files, and optionally password files. The Database Password file (orapwd*) may be placed in shared storage, or may be on each local node. This file contains the passwords of privileged user and must be available when the database in NOT open.