DataGuard Role Switching

Step 1 Verify that the primary database can be switched to the standby role.
Verify that the master database can switch to the slave role.
SELECT SWITCHOVER_STATUS from v $ DATABASE;
Idle>: wq

SWITCHOVER_STATUS
--------------------
TO STANDBY

Step 2 Initiate the switchover on the primary database.
Switch over the master database
Alter database commit to switchover to physical standby with session shutdown;

Step 3 Shut down and then mount the former primary database.
Close and mount the previous master database.

Shutdown abort;
Startup mount;

Step 4 Verify that the switchover target is ready to be switched to the primary role.
Verify that the conversion target is ready to be converted to the master database role
SWITCHOVER_STATUS
--------------------
SWITCHOVER LATENT

The value queried here is not TO_PRIMARY.
Problems may occur during the next step.

Step 5 Switch the target physical standby database role to the primary role.
Convert the target logical standby database role to the master database role.

Sys @ DEX> alter database commit to switchover to primary with session shutdown;
ALTER DATABASE COMMIT TO SWITCHOVER TO PRIMARY WITH SESSION SHUTDOWN
*
ERROR at line 1:
ORA-16139: media recovery required

Media recovery is required.

Sys @ DEX> alter database recover managed standby database disconnect from session;

Database altered.

Sys @ DEX> SELECT SWITCHOVER_STATUS from v $ DATABASE;

SWITCHOVER_STATUS
--------------------
TO PRIMARY

Sys @ DEX> alter database commit to switchover to primary with session shutdown;

Database altered.

Step 6 Open the new primary database.
Open a new master database
Sys @ DEX> alter database open;

Database altered.

Step 7 Verify the switch role.
Verify role conversion

Master database execution
Sys @ DEX> alter system switch logfile;

System altered.

Sys @ DEX> select sequence # from v $ log;

SEQUENCE #
----------
40
41
42

Sys @ DEX>

Standby database execution

Sys @ DEX> select sequence # from v $ log;

SEQUENCE #
----------
40
42
41

Sys @ DEX>