Maybe we want to test Failover, although the Primary is working fine. After the failover succeeded, we have an OLD Primary then and a NEW Primary. There is a well documented way to convert the OLD Primary into a Standby. This procedure is called Reinstate. This posting shows how to make the NEW Primary a Standby again. The OLD Primary will keep on running as Primary – with all productive users connected there still. A special case why we may want to do that is because we tested Failover to a Snapshot Standby that has no network connection to the Primary.
The initial configuration:
DGMGRL> show configurationConfiguration - myconf Protection Mode: MaxPerformance Databases: prima - Primary database physt - Physical standby databaseFast-Start Failover: DISABLEDConfiguration Status:SUCCESS
The version is still 11.2.0.1 like in the previous posting. I will now failover to physt while prima keeps running. Attention: If there is a productive service started on the NEW Primary, make sure to stop it. Else new productive connections will access the NEW Primary! We will deliberately cause a Split Brain situation here with two Primary Databases. This may cause problems in a productive environment and is not recommended.
DGMGRL> failover to physt;Performing failover NOW, please wait...Error: ORA-16600: not connected to target standby database for failoverFailed.Unable to failoverDGMGRL> exit[oracle@uhesse ~]$ dgmgrl sys/oracle@phystDGMGRL for Linux: Version 11.2.0.1.0 - 64bit ProductionCopyright (c) 2000, 2009, Oracle. All rights reserved.Welcome to DGMGRL, type "help" for information.Connected.DGMGRL> failover to physt;Performing failover NOW, please wait...Failover succeeded, new primary is "physt"
The error above shows that we cannot failover, connected to the (still working) Primary but must connect to the Standby first. Now there are two Primary Databases:
[oracle@uhesse ~]$ sqlplus sys/oracle@physt as sysdbaSQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:25:51 2012Copyright (c) 1982, 2009, Oracle. All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionsSQL> select database_role from v$database;DATABASE_ROLE----------------PRIMARYSQL> connect sys/oracle@prima as sysdbaConnected.SQL> select database_role from v$database;DATABASE_ROLE----------------PRIMARY
I want to make the NEW Primary a Standby again. Similar to a Reinstate, that needs Flashback Logs. My two Databases generate Flashback Logs, so that requirement is met.
SQL> connect sys/oracle@physt as sysdbaConnected.SQL> shutdown immediateDatabase closed.Database dismounted.ORACLE instance shut down.SQL> startup mountORACLE instance started.Total System Global Area 313159680 bytesFixed Size 2212936 bytesVariable Size 264244152 bytesDatabase Buffers 41943040 bytesRedo Buffers 4759552 bytesDatabase mounted.SQL> flashback database to before resetlogs;Flashback complete.SQL> alter database convert to physical standby;Database altered.This modified the controlfile and puts the Instance in NOMOUNT. We need to restart into MOUNT:
SQL> shutdown immediateORA-01507: database not mountedORACLE instance shut down.SQL> startup mountORACLE instance started.Total System Global Area 313159680 bytesFixed Size 2212936 bytesVariable Size 264244152 bytesDatabase Buffers 41943040 bytesRedo Buffers 4759552 bytesDatabase mounted.SQL> recover managed standby database using current logfile disconnect;Media recovery complete.SQL> select status,sequence# from v$managed_standby where process='MRP0';STATUS SEQUENCE#------------ ----------WAIT_FOR_LOG 12We want to see here APPLYING LOG – the redo is not yet transmitted from the OLD Primary.
SQL> connect sys/oracle@prima as sysdbaConnected.SQL> select sequence# from v$log where status='CURRENT'; SEQUENCE#---------- 13SQL> alter system set log_archive_dest_2='service=physt db_unique_name=physt';System altered.SQL> alter system set log_archive_dest_state_2=enable;System altered.SQL> alter system switch logfile;System altered.SQL> connect sys/oracle@physt as sysdbaConnected.SQL> select status,sequence# from v$managed_standby where process='MRP0';STATUS SEQUENCE#------------ ----------APPLYING_LOG 15Everything is fine now on the Database Layer: OLD Primary is still Primary, NEW Primary is again Standby, applying Redo from the OLD Primary. Only the Data Guard Broker is confused now – we need to create a new configuration:
[oracle@uhesse ~]$ dgmgrl sys/oracle@primaDGMGRL for Linux: Version 11.2.0.1.0 - 64bit ProductionCopyright (c) 2000, 2009, Oracle. All rights reserved.Welcome to DGMGRL, type "help" for information.Connected.DGMGRL> show configuration;ORA-16795: the standby database needs to be re-createdConfiguration details cannot be determined by DGMGRL[oracle@uhesse ~]$ sqlplus sys/oracle@physt as sysdbaSQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:46:13 2012Copyright (c) 1982, 2009, Oracle. All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionsSQL> alter system set dg_broker_start=false;System altered.SQL> connect sys/oracle@prima as sysdbaConnected.SQL> alter system set dg_broker_start=false;System altered.SQL> exitDisconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing options[oracle@uhesse ~]$ rm $ORACLE_HOME/dbs/dr*The above deleted the Broker Config Files. Now we create a new Broker Configuration:
[oracle@uhesse ~]$ sqlplus sys/oracle@physt as sysdbaSQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:48:22 2012Copyright (c) 1982, 2009, Oracle. All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionsSQL> alter system set dg_broker_start=true;System altered.SQL> connect sys/oracle@prima as sysdbaConnected.SQL> alter system set dg_broker_start=true;System altered.[oracle@uhesse ~]$ dgmgrl sys/oracle@primaDGMGRL for Linux: Version 11.2.0.1.0 - 64bit ProductionCopyright (c) 2000, 2009, Oracle. All rights reserved.Welcome to DGMGRL, type "help" for information.Connected.DGMGRL> create configuration mycon as primary database is prima connect identifier is prima;Configuration "mycon" created with primary database "prima"DGMGRL> add database physt as connect identifier is physt maintained as physical;Database "physt" addedDGMGRL> enable configuration;Enabled.DGMGRL> show configuration;Configuration - mycon Protection Mode: MaxPerformance Databases: prima - Primary database physt - Physical standby databaseFast-Start Failover: DISABLEDConfiguration Status:SUCCESS
That was it :-)
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