Switchover with No Broker

Performing Switchover with No Broker (Manual)

Overview:

A switchover is a role reversal between the primary database and one of its standby databases. A switchover operation guarantees no data loss. This is typically done for planned maintenance of the primary system. During a switchover, the primary database transitions to a standby role and the standby database transitions to the primary role. The transition occurs without having to recreate either database.

0. Enviroment
1. Pre-Switchover tasks
2. Steps to perform switchover with Physical Standby databases
3. Additional Information


0. Enviroment

Primary:

		Platform: Linuxx86_64
		Server Name: RAC1.RAJASEKHAR.COM, IP: 192.168.2.101
		DB Version: Oracle 11.2.0.3, File system: ASM
		DB Name: w5005pr, DB_UNIQUE_NAME: w5005pr; Non-RAC
		Flashback: Disabled
		Oracle Home Path: /u01/app/oracle/product/11.2.0/db_1
		
Standby:
		
		Platform: Linuxx86_64
		Server Name: RAC2.RAJASEKHAR.COM, IP: 192.168.2.102
		DB Version: Oracle 11.2.0.3, , File system: ASM
		DB Name: w5005pr, DB_UNIQUE_NAME: w5005prg; Non-RAC
		Flashback: Disabled
		Oracle Home Path: /u01/app/oracle/product/11.2.0/db_1


1. Pre-Switchover tasks

– Verify that there is network connectivity between the primary and standby locations.
– Always recommened test the switchover in your testing system befre working on production.
– Verify primary database READ WRITE and standby instance mounted.
– Verify there are no active users connected to database.
– Make sure last redo data transmitted from primary to standby and applied.
– Set job_queue_processes=0 and aq_tm_processes = 0, dbwr_io_slaves = 0 on both Primary and DR
alter system set job_queue_processes=0 ;
alter system set aq_tm_processes = 0 ;
alter system set dbwr_io_slaves = 0 ;

On Primary

	
SQL> select name, open_mode, database_role, INSTANCE_NAME from v$database,v$instance;

NAME      OPEN_MODE            DATABASE_ROLE    INSTANCE_NAME
--------- -------------------- ---------------- ----------------
W5005PR   READ WRITE           PRIMARY          w5005pr

SQL> select max(sequence#) from v$archived_log where archived='YES';

MAX(SEQUENCE#)
--------------
            20

SQL> select name from v$datafile where status='OFFLINE';

no rows selected

SQL> select * from dba_jobs_running;

no rows selected

SQL> show parameter job_queue_processes

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
job_queue_processes                  integer     1000
SQL>

Note: Block further job submission by setting the job_queue_processes parameter to 0 so that 
there would be no jobs running during switchover.

SQL> alter system set job_queue_processes=0 scope=spfile;

System altered.

SQL>

On Standby

SQL> select name, open_mode, database_role, INSTANCE_NAME from v$database,v$instance;

NAME      OPEN_MODE            DATABASE_ROLE    INSTANCE_NAME
--------- -------------------- ---------------- ----------------
W5005PR   READ ONLY WITH APPLY PHYSICAL STANDBY w5005prg

SQL>  select max(sequence#) from v$archived_log where applied='YES';

MAX(SEQUENCE#)
--------------
            20

SQL> select name from v$datafile where status='OFFLINE';

no rows selected

SQL> 


2. Steps to perform switchover with Physical Standby databases

On PRIMARY

Note: Always perform the switchover of the primary database to standby database first and then 
switchover the standby database to primary. 

SQL> select name, open_mode, database_role, INSTANCE_NAME from v$database,v$instance;

NAME      OPEN_MODE            DATABASE_ROLE    INSTANCE_NAME
--------- -------------------- ---------------- ----------------
W5005PR   READ WRITE           PRIMARY          w5005pr

SQL>

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
TO STANDBY

SQL>

Note: If status “TO STANDBY” or “SESSIONS ACTIVE” on the primary database, then perform the switchover
using the below query

SQL> alter database commit to switchover to physical standby with session shutdown;

Database altered.

SQL>
SQL> shut immediate;
ORA-01092: ORACLE instance terminated. Disconnection forced
SQL> exit
[oracle@rac1 ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Sun Jan 10 01:15:12 2016

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup nomount;
ORACLE instance started.

Total System Global Area 1269366784 bytes
Fixed Size                  2227984 bytes
Variable Size             822083824 bytes
Database Buffers          436207616 bytes
Redo Buffers                8847360 bytes
SQL> alter database mount standby database;

Database altered.

SQL> alter database open;

Database altered.

SQL> alter database recover managed standby database disconnect from session;

Database altered.

SQL> select name, open_mode, database_role, INSTANCE_NAME from v$database,v$instance;

NAME      OPEN_MODE            DATABASE_ROLE    INSTANCE_NAME
--------- -------------------- ---------------- ----------------
W5005PR   READ ONLY WITH APPLY PHYSICAL STANDBY w5005pr

SQL>  select max(sequence#) from v$archived_log where applied='YES';

MAX(SEQUENCE#)
--------------
            22

On STANDBY

SQL> select name, open_mode, database_role, INSTANCE_NAME from v$database,v$instance;

NAME      OPEN_MODE            DATABASE_ROLE    INSTANCE_NAME
--------- -------------------- ---------------- ----------------
W5005PR   READ ONLY WITH APPLY PHYSICAL STANDBY w5005prg
SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
SESSIONS ACTIVE

SQL> alter database recover managed standby database cancel;

Database altered.

SQL> alter database commit to switchover to primary with session shutdown;

Database altered.

SQL> select name, open_mode from v$database;

NAME      OPEN_MODE
--------- --------------------
W5005PR   MOUNTED

SQL> alter database open;

Database altered.

SQL> select name, open_mode, database_role, INSTANCE_NAME from v$database,v$instance;

NAME      OPEN_MODE            DATABASE_ROLE    INSTANCE_NAME
--------- -------------------- ---------------- ----------------
W5005PR   READ WRITE           PRIMARY          w5005prg

SQL> SQL> ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=ENABLE scope=both;

System altered.

SQL> select max(sequence#) from v$archived_log where archived='YES';

MAX(SEQUENCE#)
--------------
            22

SQL>


3. Additional Information

The SWITCHOVER_STATUS column of v$database can have the following values:

NOT ALLOWED - Either this is a standby database and the primary database 
              has not been switched first, or this is a prstimary 
              database and there are no standby databases.

SESSIONS ACTIVE - Indicates that there are active SQL sessions attached
                  to the primary or standby database that need to be 
                  disconnected before the switchover operation is 
                  permitted.

SWITCHOVER PENDING - This is a standby database and the primary database 
                     switchover request has been received but not 
                     processed.

SWITCHOVER LATENT - The switchover was in pending mode, but did not 
                    complete and went back to the primary database.

TO PRIMARY - This is a standby database, with no active sessions, that is 
             allowed to switch over to a primary database. 

TO STANDBY - This is a primary database, with no active sessions, that is 
             allowed to switch over to a standby database.

RECOVERY NEEDED - This is a standby database that has not received the 
                  switchover request. 

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