Scenario 11: Reinstating a Failed Primary Database

If your former primary database was configured with Flashback Database, you can easily reinstate the failed primary database as a standby database of the new primary database.

The failed primary database will be reinstated as a standby type that matches the old standby database. For example, if you failed over to a physical standby database, the old primary will be reinstated as a physical standby database.

To reinstate the failed primary database, start it to the mounted state. Then run DGMGRL, connect to the new primary database and reinstate the old primary database.

1. Restart the old primary database:

   % dgmgrl / as sysdba
   DGMGRL for Linux: Release 23.0.0.0.0 – Production on Tue Dec 20 00:50:10 2022
   Version 23.1.0.0.0
   
   Copyright (c) 1982, 2022, Oracle and/or its affiliates.  All rights reserved.
   
   Welcome to DGMGRL, type "help" for information.
   Connected to an idle instance.
   Connected as SYSDBA.
   DGMGRL> STARTUP
   Connected to "North_Sales"
   ORACLE instance started.
   Database mounted.
   ORA-16649: Data Guard prevented this database from opening.
   https://docs.oracle.com/error-help/db/ora-16649/
   
   DGMGRL> SHOW CONFIGURATION
   
   Configuration - DRSolution
   
     Protection Mode: MaxAvailability
     Members:
     North_Sales - Primary database
       South_Sales - Physical standby database 
   
   Fast-Start Failover:  Disabled
   
   Configuration Status:
   DISABLED
   DGM-17290: Role change detected. This database may no longer be the primary database.
   

   Note:

   Because a role transition occurred while the old primary was offline, Data Guard prevents the database from reopening and leaves it in a mounted state to ensure there is only one database open in the primary role.
2. Reinstating the old primary database as a standby database requires a connection to the new primary database:

   DGMGRL> CONNECT sys@south_sales
   Password: password
   Connected to "South_Sales"
   Connected as SYSDBA.
   DGMGRL> REINSTATE DATABASE 'North_Sales';
   2022-12-20T01:06:56.636+00:00
   Reinstating database "North_Sales", please wait...
   
   2022-12-20T01:07:25.747+00:00
   Reinstatement of database "North_Sales" succeeded
   
   2022-12-20T01:07:25.747+00:00
   Reinstate processing complete, broker ready.
   

   After the primary has been reinstated, issue the SHOW CONFIGURATION and SHOW DATABASE commands to confirm that the old primary has been successfully reinstated.

3. Show the configuration and its members:

   DGMGRL> SHOW CONFIGURATION;
   
   Configuration - DRSolution
   
     Protection Mode: MaxAvailability
     Members:
     South_Sales - Primary database
       North_Sales - Physical standby database 
   
   Fast-Start Failover:  Disabled
   
   Configuration Status:
   SUCCESS   (status updated 22 seconds ago)
   
   DGMGRL> SHOW DATABASE 'South_Sales';
   
   Database - South_Sales
   
     Role:                PRIMARY
     Intended State:      TRANSPORT-ON
     Redo Rate:           146 Byte/s  in 15 seconds (computed 9 seconds ago) 
     Instance(s):
       SouthSales
   
   Database Status:
   SUCCESS
   
   DGMGRL> SHOW DATABASE 'North_Sales';
   
   Database - North_Sales
   
     Role:                PHYSICAL STANDBY
     Intended State:      APPLY-ON
     Transport Lag:       0 seconds (computed 1 second ago)
     Apply Lag:           0 seconds (computed 1 second ago)
     Average Apply Rate:  435.00 KByte/s
     Real Time Query:     OFF
     Instance(s):
       NorthSales
   
   Database Status:
   SUCCESS