Oracle Manual DB Switchover: Primary to Standby with DGMGRL

A switchover in Oracle Data Guard is a planned role reversal between the primary and standby databases, ensuring minimal downtime. This guide provides a step-by-step process to manually switch from the primary database to a physical standby database using DGMGRL in Oracle.

Prerequisites

Before performing the switchover, ensure the following:

Data Guard is properly configured between the primary and standby databases.
Both databases are in sync.
You have SYSDBA privileges.

Step 1: Set the ORACLE_SID

Before using DGMGRL, set the ORACLE_SID to match your database instance:

Step 2: Connect to DGMGRL

Run the following command to connect to DGMGRL as SYSDBA:

dgmgrl sys/<PASSWORD>@<PRIMARY_DB>

Step 3: Validate the Database Readiness

Run the following command to connect to DGMGRL as SYSDBA:

DGMGRL> validate database <PRIMARY_DB>;

Expected output should confirm:

Database Role: Primary database
Ready for Switchover: YES
Managed by Clusterware: YES

Step 4: Perform the Switchover

Execute the following command in DGMGRL:

DGMGRL> switchover to <STANDBY_DB>;

Expected Output:

Performing switchover NOW, please wait...
Operation requires a connection to database "<STANDBY_DB>"
Connecting ...
Connected to "<STANDBY_DB>"
Connected as SYSDBA.
New primary database "<STANDBY_DB>" is opening...
Oracle Clusterware is restarting database "<PRIMARY_DB>" ...
Connected to "<PRIMARY_DB>"
Switchover succeeded, new primary is "<STANDBY_DB>"

What Happens During This Step?

The command switches roles between primary and standby.
Oracle connects to the target standby database.
The new primary database is opened.
The former primary is converted into a standby database.

Step 5: Verify the Switchover

Ensure that:

The former standby is now the primary.
The former primary is now the standby.

Step 6: Update OND Hostnames

If your environment uses OND hostnames, update them accordingly to reflect the new primary and standby servers.

Additional Considerations

If you encounter issues, check the alert logs and Data Guard broker logs.
If using Fast-Start Failover (FSFO), ensure it is properly reconfigured.

Conclusion

Performing a manual switchover in Oracle Data Guard ensures seamless role transitions between databases. This method is useful for maintenance activities, disaster recovery testing, and planned database role changes.