Oracle Active/Active Configurations

An active/active configuration consists of at least two servers, each running a different database instance. The databases must be on different shared disks.

$ORACLE_HOME can be on non-shared or on shared disks depending upon the configuration requirements. For example, multiple database instances on any of the servers using a common $ORACLE_HOME require $ORACLE_HOME to be on non-shared disks. If the $ORACLE_HOME directories are on shared disk, they must be on separate shared disks.

This section provides two active/active configuration examples, shown in Figure 3 and Figure 4:

• Databases on shared resources and a common $ORACLE_HOME on non-shared resources.
  

• Databases on shared resources and the appropriate $ORACLE_HOME instance on the same shared resource.
  

Note: Multiple database instances on one server using multiple instances of $ORACLE_HOME on non-shared resources are not illustrated.

Configuration Notes:

1. 
   
2. The server has its own $ORACLE_HOME directory on a non-shared disk. Each server has the same version of the Oracle application.

3. The $ORACLE_HOME path is the same on both servers.

4. The databases, databaseA and databaseB, are on shared disks.

5. The oratab file exists in /etc/ on both servers, containing entries for both Oracle instances.

6. Initially, Server 1 runs databaseA and Server 2 runs databaseB. In a switchover situation, one system can run both databases.

7. See Creating Oracle Database Hierarchy After Installing Oracle Binaries on Local Storage for further information.
   

Configuration Notes:

1. 
   
2. Both servers use an $ORACLE_HOME directory on different shared disks.

3. The Oracle application is the same on both servers. The $ORACLE_HOME is different for each instance defined on the server.

4. The databases, databaseA and databaseB, are on shared disks.

5. The oratab file exists in /etc/, containing entries for both Oracle instances.

6. A unique login is required for each Oracle instance. The id and gid for each login should be the same on Server 1 and Server 2.

7. Initially, Server 1 runs databaseA and Server 2 runs databaseB. In a switchover situation, one system can run both databases.