To use the RAC failover feature, you must have a minimum
10g version of Oracle.
Oracle provides technology called Real Application Clusters (RAC), which allows an Oracle database to run in a clustered environment; in other words, the database can be serviced by several Oracle instances spread across several host machines. In this clustered environment, a “virtual instance” will direct and redirect instance connections from one instance to another when failover occurs. If an instance fails, the client is failed over to a secondary instance in the RAC environment. The Sybase® Enterprise Connect Data Access Option for Oracle uses the Oracle feature called Transparent Application Failover (TAF) to provide this failover function.
When a heterogeneous environment includes an Oracle RAC environment, ECDA Option for Oracle support of TAF helps prevent an outage due to an Oracle instance failure, and as a result, reduces downtime in operations.
In support of Oracle RAC, ECDA Option for Oracle manages the failover from one instance to another as follows:
It connects to an Oracle database instance participating in an Oracle RAC environment.
When failure occurs, it sends the ECDA Option for Oracle client connection to alternate Oracle instances that are defined in the ECDA Option for Oracle tnsnames.ora file.
It reports any error messages resulting from a failover to the client application.
If all backup instances are unavailable, an ORA-03113
error is sent back to the client application.
