Dataguard FAQ

1. What are the types of Oracle Data Guard?
Oracle Data Guard classified in to two types
based on way of creation and method used for Redo Apply. They are as follows.
1.Physical standby (Redo Apply technology)
2.Logical standby (SQL Apply Technology)

2. What are the advantages in using Oracle Data Guard?
Following are the different benefits in using Oracle Data Guard feature in your environment.
1.High Availability.
2.Data Protection.
3.Off loading Backup operation to standby database.
4.Automatic Gap detection and Resolution in standby database.
5.Automatic Role Transition using Data Guard Broker.

3. What are the different services available in Oracle Data Guard?
Following are the different Services available in Oracle Data Guard of Oracle database
1.Redo Transport Services.
2.Log Apply Services.
3.Role Transitions.

4. What are the different Protection modes available in Oracle Data Guard?
Following are the different protection modes available in Data Guard of Oracle database you can use any one based on your application requirement.
1.Maximum Protection
2.Maximum Availability
3.Maximum Performance

5. How to check what protection mode of primary database in your Oracle Data Guard?
By using following query you can check protection mode of primary database in your Oracle Data Guard setup.

SELECT PROTECTION_MODE FROM V$DATABASE;

For Example:
SQL> select protection_mode from v$database;
PROTECTION_MODE
——————————–
MAXIMUM PERFORMANCE

6. How to change protection mode in Oracle Data Guard setup?
By using following query your can change the protection mode in your primary database after setting up required value in corresponding LOG_ARCHIVE_DEST_n parameter
in primary database for corresponding standby database.

ALTER DATABASE SET STANDBY DATABASE TO MAXIMUM [PROTECTION|PERFORMANCE|AVAILABILITY];

Example:
alter database set standby database to MAXIMUM PROTECTION;

7. What are the advantages of using Physical standby database in Oracle Data Guard?
Advantages of using Physical standby database in Oracle Data Guard are as follows.
■High Availability.
■Load balancing (Backup and Reporting).
■Data Protection.
■Disaster Recovery.

8. What is physical standby database in Oracle Data Guard?

Physical standby database are created as exact copy i.e block by block copy of primary database.

In physical standby database transactions happen in primary database are synchronized in standby database by
using Redo Apply method by continuously applying redo data on standby database received from primary database.

Physical standby database can offload the backup activity and reporting activity from Primary database.

Physical standby database can be opened for read-only transactions but redo apply won’t happen during that time. But from 11g onwards using Active Data Guard option (extra purchase) you can simultaneously open the physical standby database for read-only access and apply redo logs received from primary database.

9.What is Logical standby database in Oracle Data Guard?

Logical standby database can be created similar to Physical standby database and later you can alter the structure of logical standby database.
Logical standby database uses SQL Apply method to synchronize logical standby database with primary database.

This SQL apply technology converts the received redo logs to SQL statements and continuously apply those SQL statements on logical standby
database to make standby database consistent with primary database.

Main advantage of Logical standby database compare to physical standby database is you can use Logical standby database for reporting purpose during SQL apply
i.e Logical standby database must be open during SQL apply.

Even though Logical standby database are opened for read/write mode,

Though Logical standby database has advantage on Physical standby database it has some restriction on data-types, types of DDL, types of DML and types of tables.

10. What are the advantages of Logical standby database in Oracle Data Guard?
■Better usage of resource
■Data Protection
■High Availability
■Disaster Recovery

11. What is the usage of DB_FILE_NAME_CONVERT parameter in Oracle Data Guard setup?
DB_FILE_NAME_CONVERT parameter is used in Oracle Data Guard setup that to in standby databases.
DB_FILE_NAME_CONVERT parameter are used to update the location of data files in standby database.
These parameter are used when you are using different directory structure in standby database compare to primary database data files location

12. Can Oracle’s Data Guard be used on Standard Edition, and if so how? How can you test that the standby database is in sync?

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