Configure tnsnames.ora file for Transparent application Failover using Scan in Oracle RAC

Open tnsnames.ora file which is installed on Oracle Client Server or Application Server which connect to Oracle RAC environment. You need to create a tns-entry in tnsnames.ora file to configure TAF using SCAN as follows:

To configure TAF on the client side, make an entry of FAILOVER_MODE in tnsnames.ora file with Service Name. It will only switch the SELECT Statement from one node to another in case of node failure occurred in RAC Environment

RACTAF =
 (DESCRIPTION = 
   (ADDRESS = (PROTOCOL = TCP)(HOST = xxxxx)(PORT = 1521)) 
 (CONNECT_DATA =
   (SERVER = DEDICATED)
   (SERVICE_NAME = racdb)
     (FAILOVER_MODE=
       (TYPE=select)
       (METHOD=basic))))

Check the connection using the TFA parameter with the following query after configuring in TNSNAMES.ORA file on client side:

SQL> SELECT MACHINE, FAILOVER_TYPE, FAILOVER_METHOD, FAILED_OVER, COUNT(*)
FROM V$SESSION
GROUP BY MACHINE, FAILOVER_TYPE, FAILOVER_METHOD, FAILED_OVER;

MACHINE    FAILOVER_TYPE FAILOVER_M FAI COUNT(*)
--------- ------------- --------- ----- ---
XXXXXX    SELECT        BASIC    NO   1