Manual Switchover to Standby Database

We will see how to switchover the database role from primary to standby and vice versa

Switchover is the process or allowing to the primary/standby database to switch their role with their
respective primary/standby database. Where there is no any data loss during the role change this is known as switchover.

There are two main database role

              1)    Primary database

              2)    Standby database

Primary Database:-

           Is the database where all the active user connection are coming from end user.

Standby Database:-

      The database is connected to primary database any work happens  on the primary database will get reflect to standby database in the form of redo data. In some times it is used for reporting purpose (read only) mode.

Before going to switch over need to consider below things.

       1)      Standby database need to be in sync with primary.

       2)      Check network connection between primary and standby it need to be active

       3)      Check Standby redo logs(SRL’s) are configured on primary side.

Starting Manual Switchover

      1)      On Primary Database

      

          1.1) check switchover status

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS

-----------------------------

To STANDBY

Note:- You will get output  Active session OR  To standby

1.2)  Change the switchover status

SQL> Alter database commit to switchover to physical standby with session shutdown;

Database altered

SQL> shutdown immediate

SQL> startup nomount

SQL>alter database mount standby database;

       2)    On Standby Database

          

            2.1) check the switchover status

      SQL> select switchover_status from v$database;

      SWITCHOVER_STATUS

       --------------------

      TO PRIMARY

      2.2) Stop the Managed Recovery Process (MRP)

      SQL> alter database recover managed standby database cancel;

       2.3) execute below command to switchover standby database to Primary

       SQL> Alter database commit to switchover to primary;

       SQL> shut immediate

       SQL> startup

       2.4) now check the database role it is now primary.

       SQL> select name,open_mode,database_role from v$database;

       NAME     OPEN_MODE DATABASE_ROLE

        --------- -------------------- ----------------

       TESTDB    READ WRITE PRIMARY

     3)  Now on  newly created standby database start Recovery (MRP)

       SQL>alter database recover managed standby database disconnect from session;

        Media recovery completed

.