Steps to switchover standby to primary

SWITCHOVER PRIMARY TO STANDBY DATABASE

Primary =PRIM
Standby = STAN
I. Before Switchover:
1. As I always recommend, test the Switchover first on your testing systems before working on Production.
2. Verify the primary database instance is open and the standby database instance is mounted.
3. Verify there are no active users connected to the databases.
4. Make sure the last redo data transmitted from the Primary database was applied on the standby database. Issue the following commands on Primary database and Standby database to find out:
SQL>select sequence#, applied from v$archvied_log;
Perform SWITCH LOGFILE if necessary.
In order to apply redo data to the standby database as soon as it is received, use Real-time apply.
II. Quick Switchover Steps
1. Initiate the switchover on the primary database PRIM:
SQL>connect /@PRIM as sysdba
SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PHYSICAL STANDBY WITH SESSION SHUTDOWN;
2. After step 1 finishes, Switch the original physical standby db STAN to primary role;
Open another prompt and connect to SQLPLUS:
SQL>connect /@STAN as sysdba
SQL> ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY;
3. Immediately after issuing command in step 2, shut down and restart the former primary instance PRIM:
SQL>SHUTDOWN IMMEDIATE;
SQL>STARTUP MOUNT;
4. After step 3 completes:
- If you are using Oracle Database 10g release 1, you will have to Shut down and restart the new primary database STAN.
SQL>SHUTDOWN IMMEDIATE;
SQL>STARTUP;
- If you are using Oracle Database 10g release 2, you can open the new Primary database STAN:
SQL>ALTER DATABASE OPEN;
STAN is now transitioned to the primary database role.
5. On the new primary database STAN, perform a SWITCH LOGFILE to start sending redo data to the standby database PRIM.
SQL>ALTER SYSTEM SWITCH LOGFILE;