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Wednesday 18 August 2021

Configure Data Guard Broker

 Benefits of Data Guard Broker


One of the biggest benefits of Data Guard broker is that is centralizes the configuration, management and monitoring of Oracle Data Guard configurations.

Some of the operations that Data Guard broker simplifies are

  • Create Data Guard configuration between primary and standby databases

  • Add additional standby databases to existing Data Guard configuration

  • Mange Data Guard protection modes

  • Start switchover / failover by just one single command

  • Automate failover in case of primary not reachable

  • Monitor redo apply, gaps and data guard performance

  • Perform all above operations locally or remotely !



1) Stop MRP on standby

=============================

We would like to manage our data guard configuration using Data Guard Broker. Stop MRP and clear Log_Archive_dest_2 parameter


On standby:
===========

SQL> alter database recover managed standby database cancel;



SQL> alter system set LOG_ARCHIVE_DEST_2='' SCOPE=BOTH;





On primary:
===========
SQL> alter system set LOG_ARCHIVE_DEST_2='' SCOPE=BOTH;






Connect to both databases (primary and standby) and issue the following command
==================================================

On primary:
===========

ALTER SYSTEM SET dg_broker_start=true; --------Primary

show parameter dg_broker_start;

SQL> show parameter dg_broker

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
dg_broker_config_file1               string      /u01/app/oracle/product/18.3.0.0/dbs/dr1ORCL.dat
dg_broker_config_file2               string      /u01/app/oracle/product/18.3.0.0/dbs/dr2ORCL.dat
dg_broker_start                      boolean     TRUE



On standby:
===========

ALTER SYSTEM SET dg_broker_start=true; --------Standby

show parameter dg_broker_start;

SQL> show parameter dg_broker

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
dg_broker_config_file1               string      /u01/app/oracle/product/18.3.0.0/dbs/dr1ORCL.dat
dg_broker_config_file2               string      /u01/app/oracle/product/18.3.0.0/dbs/dr2ORCL.dat
dg_broker_start                      boolean     TRUE



Register primary with broker
===========================

On primary, connect to DGMGRL utility and register the primary database with broker

dgmgrl sys/*****@ORCL

dgmgrl sys/sys#123@ORCL

Connected as SYSDBA.




Add Primary database:
==========================


DGMGRL> CREATE CONFIGURATION my_dg_config AS PRIMARY DATABASE IS ORCL CONNECT IDENTIFIER IS ORCL;

DGMGRL> show configuration;





Register standby with broker
============================

In the same DGMGRL utility, register standby from primary server itself

Add Standby database:
===========================

DGMGRL> ADD DATABASE ORCLDG AS CONNECT IDENTIFIER IS ORCLDG MAINTAINED AS PHYSICAL;

DGMGRL> show configuration;






Enable Data Guard broker
Once primary and standby are registered, we must enable broker

DGMGRL> ENABLE CONFIGURATION;
DGMGRL> SHOW CONFIGURATION;
DGMGRL> SHOW CONFIGURATION;

Configuration - my_dg_config

  Protection Mode: MaxPerformance
  Members:
  orcl   - Primary database
    orcldg - Physical standby database
      Warning: ORA-16853: apply lag has exceeded specified threshold

Fast-Start Failover: DISABLED

Configuration Status:
WARNING   (status updated 12 seconds ago)



Cause: Due to apply lag or transport lag. Check Dataguard configurations for parameter ApplyLagThreshold.
DGMGRL> show database verbose orcl;

Solution
ApplyLagThreshold configurable database property generates a warning status for a logical or physical standby when the database’s apply lag exceeds the value specified by the property.

DGMGRL> edit database ORCLDG set property DelayMins=0;

SOLUTION:
1.Check for the delaymin parametr:

DGMGRL> show database verbose orcldg DelayMins 
DelayMins = ‘0’



DGMGRL> show database ORCLDG;

Database - orcldg

  Role:               PHYSICAL STANDBY
  Intended State:     APPLY-ON
  Transport Lag:      0 seconds (computed 1 second ago)
  Apply Lag:          0 seconds (computed 1 second ago)
  Average Apply Rate: 2.00 KByte/s
  Real Time Query:    OFF
  Instance(s):
    ORCLDG

Database Status:
SUCCESS









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