Dataguard Switchover in Oracle

Hi,

I will explain you to perform Switchover in Oracle Dataguard in this article.

Before reading this article, I recommend that you read the article about Data Guard configuration and architecture with following links.

https://ittutorial.org/oracle-dataguard-architecture-3/

As I mentioned in my above posts, Dataguard is Oracle’s Disaster Recovery solution.You can open dataguard  in case of a disaster and make the database available as soon as possible.

You can perform switchover between production database and dataguard, in case of any disaster or any maintenance (ram, disk exchange etc) on the server on the Production side.

This operation we call Switchover changes the modes between Primary (Production) and Standby (Disaster or Dataguard). So the primary database will be the Standby database after this switchover, while the Standby database will be Primary database.

The steps to be performed step by step on the Production and Standby side of the switchover process are as follows. MehmetSalih server is the Production database server, and Deveci Server is Standby server in the example.

Steps on Production

Manual logfile switch is done before Switchover on Primary like following.

[oracle@MehmetSalih ~]$ sqlplus / as sysdba
SQL> alter system switch logfile;

System altered.


SQL> select switchover_status,database_role from v$database;

SWITCHOVER_STATUS DATABASE_ROLE
-------------------- ----------------
TO STANDBY PRIMARY

In this step, we perform switchover operation and our Primary database will be Physical Standby.

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

Database altered.

SQL> shutdown immediate;
ORA-01092: ORACLE instance terminated. Disconnection forced

SQL> startup nomount
ORACLE instance started.

Total System Global Area 534462464 bytes
Fixed Size 2230072 bytes
Variable Size 171968712 bytes
Database Buffers 352321536 bytes
Redo Buffers 7942144 bytes
SQL>

Mount the Old Primary Database in this step as Standby

SQL> alter database mount standby database;

Database altered.

SQL> alter system set log_archive_dest_state_2=defer;

System altered.

Steps On Dataguard

In this step, we perform switchover operation on Standby and our Standby database will be Production.

[oracle@Deveci ~]$ sqlplus / as sysdba

SQL> select switchover_status,database_role from v$database;

SQL> alter database commit to switchover to primary with session shutdown;

Database altered.


SQL> shutdown immediate;

SQL> startup
ORACLE instance started.

Total System Global Area 534462464 bytes
Fixed Size 2230072 bytes
Variable Size 163580104 bytes
Database Buffers 360710144 bytes
Redo Buffers 7942144 bytes
Database mounted.
Database opened.

Now the MRP process on the new Standby side ( Old Production ) is run  as follows.

SQL> alter database recover managed standby database using current logfile disconnect;

Database altered.

SQL>

Now Switchover operation is completed. You can do same steps to reverse them.

You can perform Dataguard switchover using Dataguard broker dgmgrl, if you want to learn it, you can read the following post.

What is the Oracle Dataguard Broker and How to Enable / Disable Dataguard Broker Configurations

Do you want to learn Oracle Database for Beginners, then read the following articles.

https://ittutorial.org/oracle-database-19c-tutorials-for-beginners/