Oracle Dataguard 11g Doc V1.01

8/6/2019 Oracle Dataguard 11g Doc V1.01

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Oracle Data Guard 11g

Basic Concept, ImplementationAnd Administration

Author: Muhammad Aamir

Creation date: 07th

January, 2011

Doc version: 1.0

Change Control:

Change Record

Date Author Version Change Reference

07/01/2011 Muhammad Amir 1.0 Document Created


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Oracle Dataguard Concepts V1.0

Muhammad Aamir Copyrights reserved Page 2 of20

1. Introduction

This document is intended to serve as definitive reference of Oracle Data Guard technology and

concepts, and helps you configure and implement physical standby databases. Oracle Data Guard is the

most effective solution available today to protect the core asset of any enterpriseits data, and make it

available on a 24x7 basis even in the face of disasters and other calamities.

2. Concepts

A Data Guard configuration consists of one production database and one or more standby databases.

The databases in a Data Guard configuration are connected by Oracle Net and may be dispersed

geographically. There are no restrictions on where the databases are located, provided they can

communicate with each other. Figure 1 shows a typical Data Guard Configuration that contain primary

database that transmit redo data to standby database

The following data guard services manages the transmission of redo data, the application of redo data,

and changes to the database role

- Redo transport services

Control the automated transfer of redo data from the production database to one or more archival

destinations.

- Apply services

Apply redo data on the standby database to maintain transactional synchronization with the primary

databases. Redo can be applied either from archival redo log files or if real time apply is enabled,

directly from standby redo log files

- Role transition

This service changes the role of a database from standby database to primary or from primary

database to standby database using either a switchover or failover operations.

You can use to manage Data Guard using the SQL command-line interfaces or the Data Guard broker

interfaces, including a command-line interface (DGMGRL) and a graphical user interface that is

integrated in Oracle Enterprise Manager

Figure 1 : Typical Data Guard Configuration


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3. Creating Physical standby database Using RMAN

In this section you create a Data Guard physical standby database using RMAN active database

duplication and we are using the following pre-configured Virtual Machines with the configuration given

below.

Assumptions:

- Operating System: Oracle Enterprise Linux 5 update 3 32 bit (complete installation)

- Oracle Software: Oracle 11g Release 2 - 32 bit with latest patches

- Memory (Each VM Server): 1.5 GB

- Swap Space (Each VM Server): 3 GB

- Preconfigured database on primary machine

- Installation of Oracle binaries on standby machine

- Connectivity between nodes (Entries in host file of both nodes)

And the following configuration use for host name and databases

Primary Standby

Hostname dgprim.tap.com dgstby.tap.com

Global Db name prim.tap.com stby.tap.com

Db_unique_name Prim Stby

Oracle SID Prim Stby

Listener Ports 1521 1521

TNS_NAMES Prim Stby

Listener LISTENER(with static service entry) LISTENER (with static service entry)

ORACLE_BASE /u01/app/oracle /u01/app/oracle

ORADATA /u01/app/oracle/oradata/prim/ /u01/app/oracle/oradata/stby/

Archive Dest /u01/app/oracle/oradata/archive/ /u01/app/oracle/oradata/archive/

3.1. Preparing the Primary Database

On primary site we assumed that we have already running database. Firstly we must ensure that the

primary database is properly configured. Perform the following tasks on the primary database to

prepare for standby database

a.) Enable force logging

b.) Add standby log files on primary database (it is recommended to create standby redo logs on

primary database to make things easier during switchover and failover), standby log files are

required to store redo received from primary database, and must have at least one more redo log

group than the redo log on the primary database.


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Verify standby log files

c.) Set the log_archive_config parameter, this parameter enables the full data Guard functionality and

it contains the db_unique_name of each database in the configuration.

d.) Set the log_archive_dest_2 parameter to specify the destination of the remote physical standbymachine where it transmits the redo data.

e.) Set standby_file_management parameter, its made changes automatically into standby database

when data files are added or dropped from the primary database

f.) Enable archiving if it is not enable

SQL>Shutdownimmediate;SQL>Startupmount;SQL>Alterdatabasearchivelog;SQL>Alterdatabaseopen;


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g.) Register database services into listener

h.) Add entry in tnsnames.ora


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i.) Copy tnsnames.ora to standby database using OS utility

Note: At this stage all the preparation of primary site was done now prepare standby machine

3.2. Preparing the Standby Server

On this machine we assumed that we have only installed oracle software binaries and have only

password file and tnsnames.ora file which was copy from primary site.

a.) Register static service entry for standby database in listener.ora

b.) Copy password file to standby database using OS utility

c.) Create required directories

mkdir-p/u01/app/oracle/oradata/stbymkdir-p/u01/app/oracle/flash_recovery_area


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d.) Create dummy init parameter file to start the instance on primary side

e.) Start the standby database server into no mount state

Note: At this stage all the preparation of standby site was done now we are going to run the script onprimary database which will configure standby server automatically

3.3. Run RMAN Duplicate from Primary DB

In this demonstration I Use the following RMAN script to duplicate the current primary database.

a.) Create rman script and grant executes permission to it. Cat /u01/app/oracle/backup.txt

In this script I use the duplicate target database for standbycommand which performs the actual data

movement at the standby server and for active database command is used to create the standby

database from actively running primary database and parameter_value_convert is used to convertinginstance parameter values and also set the parameters which is specifically for standby database.


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b.) Run RMAN and connect to the primary database and make an auxiliary connection to the standby

database

c.) Run RMAN and connect to the primary database and make and auxiliary connection to the standby

database

Output of the script


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Note: at the end of the script you see the finished successfully which means your standby server is ready

d.) Now you need to run the following command on STANDBY NODE to start redo Apply services

3.4. Test and Verify Standby Services

a.) Execute the query to verify the status

b.) Now at this stage your database is configured for data guard


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c.) To Use the Data guard as an active data guard restart the database and run the recovery command

as mention below. Make sure the sequence of shutdown is proper, you must shutdown primary first

and then standby and then start standby first and then primary database.

Note: Make sure the database startup and shutdown sequence is right.


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4. Performing Switchover and failover Operations

4.1. Performing a switch over to a Physical Standby DatabaseThis section describes how to perform a switch over to a physical standby database.

a.) First verify that the primary database can be switched to the standby role

b.) Issue the following SQL Statement to start the switchover on the primary database

c.) Shutdown and then mount the former primary database.

Note: at this stage in a switchover process the original primary database is a physical standby database


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d.) Now verify that the switchover target is ready to be switched to the primary role, run the query on

standby database

e.) Switch the target physical standby database role to the primary role.

f.) And then open the new primary database

g.) Verify the status of database on old standby or new primary, the role become change now.

h.) Now Start the Redo Apply services on new standby site

i.) Verify the status of new standby site


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4.2. Performing a failover to a Physical Standby Database

This section provides examples that create a broker configuration named Config1 that includes a

a.) This section describes how to perform a fail over to a physical standby database.

b.) Verify the archive log gaps make sure no gaps found.

c.) Run the following statement to initiate the failover

d.) This statement convert the standby database to the primary role

e.) If your database is not open in read only mode run the following to open the database.


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f.) Restart the database

g.) Verify the role of the database. Now your database is ready for primary role


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5. Data Guard Broker DGMGRL

This section describes you how to use DGMGRL tool to create, manage, and monitor a broker

configuration

5.1. Create and Enable Broker Configuration

This section provides examples that create a broker configuration named Config1 that includes a

primary and Standby database named prim and stby and enable the configuration

a.) To enable the Data guard Configuration you need to set the dg_broker_start parameter to TRUE on

both side primary and standby database

b.) Create the services with a specific name must be statically registered with the local listener on both

side primary and database that include the _DGMGRL. values for

the GLOBAL_DBNAME. This setting allows DGMGRL to restart instances during the course of broker

operations. Reload the listener and verify the status of services

Primary site Listener.ora


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Standby site Listener.ora

c.) Restart the listener on both side and make sure that the services registered properly.

d.) Invoke the DGMGRL to create dataguard configuration and connect with primary database


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Note: you must connect with primary database when you are configuring broker and if you connecting

remotely you must specify primary connection string

e.) Creating the broker configuration for the primary database

f.) Add your physical standby database to the configuration

g.) Use the SHOW CONFIGURATION command to verify that the stby database was added to the

configuration

h.) To Enable the entire configuration use the following command

i.) Use show command to verify the configuration status is started.


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5.2. Performing Switchover from Data guard broker

a.) Use the following statement to perform switchover


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5.3. Performing Failover from data guard broker

a.) To check the status of the dataguard configuration use the following statement from dgmgrlcommand line interface.

b.) Use the following statement to perform fail over .

c.) Verify the configuration again using show configuration command


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6. References

Following are the reference

http://wiki.oracle.com/page/Data+Guard+Architecture

http://www.oracle.com/technetwork/tutorials/index.html
http://wiki.oracle.com/page/Data+Guard+Architecturehttp://www.oracle.com/technetwork/tutorials/index.htmlhttp://www.oracle.com/technetwork/tutorials/index.htmlhttp://wiki.oracle.com/page/Data+Guard+Architecture

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Oracle Dataguard 11g Doc V1.01