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 configuration Configuration - myconf Protection Mode: MaxPerformance Databases: prima - Primary database physt - Physical standby database Fast-Start Failover: DISABLED Configuration 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 failover Failed. Unable to failover DGMGRL> exit [oracle@uhesse ~]$ dgmgrl sys/oracle@physt DGMGRL for Linux: Version 11.2.0.1.0 - 64bit Production Copyright (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 sysdba SQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:25:51 2012 Copyright (c) 1982, 2009, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> select database_role from v$database; DATABASE_ROLE ---------------- PRIMARY SQL> connect sys/oracle@prima as sysdba Connected. SQL> select database_role from v$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 sysdba
Connected.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area 313159680 bytes
Fixed Size 2212936 bytes
Variable Size 264244152 bytes
Database Buffers 41943040 bytes
Redo Buffers 4759552 bytes
Database 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 immediate
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area 313159680 bytes
Fixed Size 2212936 bytes
Variable Size 264244152 bytes
Database Buffers 41943040 bytes
Redo Buffers 4759552 bytes
Database mounted.
SQL> recover managed standby database using current logfile disconnect;
Media recovery complete.
SQL> select status,sequence# from v$managed_standby where process='MRP0';
STATUS SEQUENCE#
------------ ----------
WAIT_FOR_LOG 12
We want to see here APPLYING LOG – the redo is not yet transmitted from the OLD Primary.
SQL> connect sys/oracle@prima as sysdba
Connected.
SQL> select sequence# from v$log where status='CURRENT';
SEQUENCE#
----------
13
SQL> 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 sysdba
Connected.
SQL> select status,sequence# from v$managed_standby where process='MRP0';
STATUS SEQUENCE#
------------ ----------
APPLYING_LOG 15
Everything is fine now on the Database Layer: OLD Primary is still Primary, NEW Primary is again Standby, applying Redo from the OLD Primary. Only the Data Guard Broker is confused now – we need to create a new configuration:
[oracle@uhesse ~]$ dgmgrl sys/oracle@prima
DGMGRL for Linux: Version 11.2.0.1.0 - 64bit Production
Copyright (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-created
Configuration details cannot be determined by DGMGRL
[oracle@uhesse ~]$ sqlplus sys/oracle@physt as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:46:13 2012
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> alter system set dg_broker_start=false;
System altered.
SQL> connect sys/oracle@prima as sysdba
Connected.
SQL> alter system set dg_broker_start=false;
System altered.
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With 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 sysdba SQL*Plus: Release 11.2.0.1.0 Production on Mon Jan 16 10:48:22 2012 Copyright (c) 1982, 2009, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> alter system set dg_broker_start=true; System altered. SQL> connect sys/oracle@prima as sysdba Connected. SQL> alter system set dg_broker_start=true; System altered. [oracle@uhesse ~]$ dgmgrl sys/oracle@prima DGMGRL for Linux: Version 11.2.0.1.0 - 64bit Production Copyright (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" added DGMGRL> enable configuration; Enabled. DGMGRL> show configuration; Configuration - mycon Protection Mode: MaxPerformance Databases: prima - Primary database physt - Physical standby database Fast-Start Failover: DISABLED Configuration Status: SUCCESS
That was it 🙂
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#1 von Des. am Juli 22, 2012 - 15:21
I enjoy reading your articles, like this one, it is easy and plain simple to understand.
#2 von Rajeev am Juni 25, 2014 - 14:09
Nice Article.
But say, we don’t use DG Broker and flashback is not enabled on standby, how to re-configure (New primary) back to physical standby and streamline with the primary.
#3 von Pavan Kumar Kumar N am Dezember 24, 2014 - 15:41
Hi,
I think it may not work if the the assumption is wrong, that is primary failover is done successfully. In that case
Primary (database instance down ..as dmon will bring it down) and the physical standby will become the new primary.
Now, going back to old roles, with above procedure will may halt the primary in mount status stating
It’s old primary …
NSV started with pid=24, OS id=9787
Data Guard determines a failover has occurred – this is no longer a primary database
– Thanks
Pavan Kumar N
#4 von Gary am August 20, 2015 - 14:38
Brilliant instructions, very clear and saved a load of guesswork. Many thanks
Gary
#5 von Amit am Januar 30, 2018 - 16:13
Many thanks for your post. very educational.
Just to point that Link for “ way to convert the OLD Primary into a Standby.“ is now broken.