Example: TAF Pre-Establishing a Connection

A backup connection can be pre-established. The initial and backup connections must be explicitly specified. In the following example, clients that use net service name sales1.us.acme.com to connect to the listener on sales1-server are also preconnected to sales2-server. If sales1-server fails after the connection, Oracle Net fails over to sales2-server, preserving any SELECT statements in progress. Likewise, Oracle Net preconnects to sales1-server for those clients that use sales2.us.acme.com to connect to the listener on sales2-server.

sales1.us.acme.com=
 (DESCRIPTION=
  (ADDRESS=
       (PROTOCOL=tcp) 
       (HOST=sales1-server) 
       (PORT=1521))
  (CONNECT_DATA=
     (SERVICE_NAME=sales.us.acme.com)
     (INSTANCE_NAME=sales1)
     (FAILOVER_MODE=
       (BACKUP=sales2.us.acme.com)
       (TYPE=select)
       (METHOD=preconnect))))
sales2.us.acme.com=
 (DESCRIPTION=
  (ADDRESS=
       (PROTOCOL=tcp) 
       (HOST=sales2-server) 
       (PORT=1521))
  (CONNECT_DATA=
     (SERVICE_NAME=sales.us.acme.com)
     (INSTANCE_NAME=sales2)
     (FAILOVER_MODE=
       (BACKUP=sales1.us.acme.com)
       (TYPE=select)
       (METHOD=preconnect))))

Example: TAF Pre-Establishing a Connection

If Transparent Application Failover (TAF) is configured, a backup connection can be pre-established to the secondary instance. The initial and backup connections must be explicitly specified. In the following example, Oracle Net connects to the listener on sales1-server and preconnects to sales2-server, the secondary instance. If sales1-server fails after the connection, the TAF application fails over to sales2-server, the secondary instance, preserving any SELECT statements in progress.

sales1.acme.com=
 (DESCRIPTION=
  (ADDRESS=
       (PROTOCOL=tcp) 
       (HOST=sales1-server) 
       (PORT=1521))
  (CONNECT_DATA=
     (SERVICE_NAME=sales.us.acme.com)
     (INSTANCE_ROLE=primary)
     (FAILOVER_MODE=
       (BACKUP=sales2.acme.com)
       (TYPE=select)
       (METHOD=preconnect))))
sales2.acme.com=
 (DESCRIPTION=
  (ADDRESS=
       (PROTOCOL=tcp) 
       (HOST=sales2-server) 
       (PORT=1521))
  (CONNECT_DATA=
     (SERVICE_NAME=sales.us.acme.com)
     (INSTANCE_ROLE=secondary)))