Oracle 11g Active Dataguard


Difference between Oracle 10g Dataguard and Oracle 11g Dataguard

Active Data Guard is a new option for Oracle Database 11g Enterprise Edition

An Active Data Guard standby database is an exact copy of the primary that is open read-only while it continuously applies changes transmitted by the primary database. An active standby can offload ad-hoc queries, reporting, and fast incremental backups from the primary database, improving performance and scalability while preventing data loss or downtime due to data corruptions, database and site failures, human error, or natural disaster.  Oracle Active Data Guard enables read-only access to a physical standby database.

With Oracle Active Data Guard, a physical standby database can be used for real-time reporting, with minimal latency between reporting and production data. Compared with traditional replication methods, Active Data Guard is very simple to use, transparently supports all datatypes, and offers very high performance. Oracle Active Data Guard also allows backup operations to be off-loaded to the standby database, and be done very fast using intelligent incremental backups.

Active Dataguard Features:

1.  Physical Standby with Real-time Query

2.  Fast Incremental Backup on Physical Standby.

3.  Automatic Block Repair.

 

 

 

We can convert the physical standby into active Data Guard standby by following below steps:

1.) Stop Apply Services
SQL> alter database recover managed standby database cancel ;

2.) Shut the database and open in mount stage
SQL> shut immediate
SQL> startup mount
SQL> alter database recover managed standby database using current logfile disconnect ;
SQL> alter database open ;

It enables us to have a physical standby read only open, while redo apply is still done in the background .

How to Check if Active Data Guard is Enabled or Not:
Use the following query to confirm that Data Guard is in active mode:

SQL> select ‘Using Active Data Guard’ ADG from v$managed_standby m,v$database d where m.process like ‘MRP%’ ;
ADG
———————–
Using Active Data Guard

or from standby datbase

SQL> select open_mode,controlfile_type from v$database;
OPEN_MODE CONTROLFILE
——————– ——————
READ ONLY WITH APPLY STANDBY

If the query does not return the above result, and instead returns : no rows selected, then Active Data Guard is not enabled.


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