Live Demonstration of Dataguard Switch Over or Fail Over - DR Drill Activity

 

Do Attend Live Webinar on - "Live Demonstration of Dataguard Switch Over or Fail Over - DR Drill"

Join Zoom Meeting - Sat 05-Jun-2021 @ 7:30 PM IST

More details can be found in our DBA Telegram group @mallik034

Agenda:

1.DataGuard Switch Over Understanding

2.DataGuard Fail Over Understanding

3.Live Demonstration on Switch Over and Switch Back

4.Q&A

Details Steps:

12c Data guard Switchover Best Practices using SQLPLUS (Doc ID 1578787.1)

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Before Switch Over Environment details:

PROD Environment :

DB: ORCL

Server: oracledb.localdomain.com

Oracle Home: /u01/app/oracle/product/19.0.0.0/dbhome_1

DR Environment :

DB: ORCLSB

Server: oraclesb.localdomain.com

Oracle Home: /u01/app/oracle/product/19.0.0.0/dbhome_1

Step 1:- Verify the database is ready for switch over or not?

SQL> alter database switchover to ORCLSB verify;

Step 2:- Check database role and database name

Primary DB:

select name,open_mode,database_role from v$database;

Standby DB:

select name,open_mode,database_role from v$database;

Precheck for Switchover:-

Step 3:- Verify the state of data guard on both the databases with following SQL queries:

ALTER SESSION SET nls_date_format='DD-MON-YYYY HH24:MI:SS';

SELECT sequence#, first_time, next_time, applied FROM v$archived_log ORDER BY sequence#;

Step 4:- select switchover_status from v$database;

Not Allowed:- Either this is a standby database and the primary database has not been switched first, or this is a primary database and there are no standby databases

Session 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

Primary DB:

Step 5:-

SQL> alter database commit to switchover to standby;

Step 6:-

shutdown immediate;

startup nomount;

alter database mount standby database;

Step 7:- select name,open_mode,database_role from v$database;

alter database recover managed standby database disconnect from session;

Standby DB:

Step 8:- alter database commit to switchover to primary;

Step 9:- select name,open_mode,database_role from v$database;

After Switch Over Environment details:

PROD Environment :

DB: ORCL

Server: oracledb.localdomain.com

Oracle Home: /u01/app/oracle/product/19.0.0.0/dbhome_1

DR Environment :

DB: ORCLSB

Server: oraclesb.localdomain.com

Oracle Home: /u01/app/oracle/product/19.0.0.0/dbhome_1

Other Helpful commands:

Enable and disable log_archive_dest_state_2 / log shipping to standby:

alter system set log_archive_dest_state_2=DEFER scope=both sid='*';

alter system set log_archive_dest_state_2=enable scope=both sid='*';

Start and stop the log shipping apply at DR database:

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE disconnect from session;

alter database recover managed standby database cancel;

Regards,

Mallik