Configuring Multi Data Sources for MDS Repositories

Considerations for High Availability Oracle Database Access 4-3

4.1.2 Using Multi Data Sources with Oracle RAC

When you deploy Oracle Fusion Middleware against Oracle RAC back ends it is configured out of the box with Multi Data Sources MDS. The MDSs have constituent data sources for each RAC instance providing the database service. Oracle recommends that you add an additional data source to the MDS on the Fusion Middleware tier when you configure additional RAC instances that offer the database service. Ensure that each constituent data source that you create for the MDS are configured identically for properties in Section 4.1.3, Configuring Multi Data Sources with Oracle RAC. When you migrate the database from a non-RAC to a RAC database, you must create an equivalent, new MDS for each data source that is affected. The MDS that you create must have consistent data sources for each RAC instance. The data source values must be identical to the original single instance data source for the properties in Section 4.1.3, Configuring Multi Data Sources with Oracle RAC. . For example, if the single instance data source driver is oracle.jdbc.xa.client.OracleXADataSource, it must be oracle.jdbc.xa.client.OracleXADataSource for each constituent data source of the new Multi Data Source. Figure 4–1 Multi Data Source Configuration

4.1.2.1 Configuring Multi Data Sources for MDS Repositories

Applications that use an MDS database-based repository can be configured for high availability Oracle database access. With this configuration, failure detection, recovery, and retry by MDS, as well as by the WebLogic infrastructure result in the applications WebLogic Server Shared Storage Multi Data Source RAC Node 1 Interconnect RAC Node 2 Data Source Data Source WebLogic Server Multi Data Source Data Source Data Source 4-4 Oracle Fusion Middleware High Availability Guide read-only MDS operations being protected from Oracle RAC database planned and unplanned downtimes. MDS multi data sources are exposed as MDS repositories in the Fusion Middleware Control navigation tree. These multi data sources can be selected during deployment plan customization of application deployment, and can be used with MDS WLST commands. ■ Configuring an application to retry read-only operations To configure an application to retry the connection, you can configure the RetryConnection attribute of the applications MDS AppConfig MBean. For information about MDS configuration, see the Oracle Fusion Middleware Administrator’s Guide. ■ Registering an MDS multi data source In addition to the steps specified in Section 4.1.3, Configuring Multi Data Sources with Oracle RAC, consider the following for MDS: – The child data sources that constitute a multi data source used for an MDS Repository must be configured as non-XA data sources. – The multi data sources name must be pre-fixed with mds-. This is required so the multi data source can be recognized as an MDS repository that can be used for MDS management functionality through Fusion Middleware Control, WLST, and JDeveloper. ■ Converting a data source to a multi data source There are two considerations when converting an MDS data source to a multi data source to make sure the application is configured correctly: – If you are creating a new multi data source with a new, unique name, redeploy the application and select this new multi data source as the MDS repository during deployment plan customization. – If you want to avoid redeploying the application, you can delete the data source and recreate the new multi data source using the same name and jndi-name attributes.

4.1.2.2 Oracle RAC Configuration Requirements