11GR2 Oracle Data Guard Switchover Scenarios

This article explains Oracle 11G R2 Oracle Data Guard physical standby database switchover scenarios. We have explained already the setup of the physical standby database for Oracle 11G R2 Data Guard. Please click here for this article.

Step 1:

Step 2:

Step 3:

Scenario 1:

How to switch over the Primary database to a Standby database and the Standby database to a primary (adb -> standby, sdb->primary)

Step 1:

Check to see if the Primary database is ready to be switched over, needs to be set to “Session active” or “to primary”.

Step 2:

In the Primary DB

Step 3:

Closing the Primary DB (to be switched to standby mode), and reopening it in mount mode.

Step 4:

The Standby (to be set to Primary) database’s status should either be TO PRIMARY or SESSIONS ACTIVE.

Step 5:

To switch the standby db over to a primary (while in the Standby db).

Step 6:

Opening the (new) Primary DB.

Step 7:

Set the new Standby log so that it applies the redologs

Step 8:

The new Standby DB

If the following error appears:

– ORA-10456: cannot open standby database; media recovery session may be in progress

To change it to its old state, use the following command:

If the Primary database has become inaccessible, the Standby database should be made the Primary DB. In order to change the faulty Primary DB back to a Standby database, it’s necessary to redo all the steps from the beginning (Setup tab onwards).

Scenario 2:

Step 1:

If the faulty Primary DB can be opened in mount mode, send any archives that haven’t been sent to the standby DB (target_db_name standby db unique name).

Use the following:

Checking the updated archived files

Step 2:

If the Primary server is accessible and if there are any archived logs in the Standby db (that’s going to be switched over to the Primary), they should be copied to the new Standby-to-be server.

Run the following command afterward to save them:

Run the following:

The output:

Step 3:

If there are missing archived logs as can be seen in the example, they should be copied to the Standby DB about to be switched Over into a Primary DB and saved using the following line:

Step 4:

Cancel the redo apply in the Primary DB (which is about to switch over into Standby)

So far no errors have been encountered then proceed to Step 5.

If there’s an error, continue saving the archivelogs. If we still get error outputs after saving the archivelogs, continue to save the data.


Step 5:

Check to see if the Standby DB is ready to be switched over to a Primary DB.





Step 6:

Switching the Standby DB to Primary

Step 7:

The other Standby DBs in the environment

To switch the original Primary server (adb.sysdba.org) back into a Primary server: retrace the steps shown during setup to StandBY mode and then switch over to Primary.


It may be necessary to update “LOG_ARCHIVE_DEST”.


Useful resources for further reading:


http://www.troug.org/?page_id=42 (Uğur İnal)