Oracle 19c Active Data Guard Configuration on Linux – Step by Step

Oracle Active Data Guard provides high availability, data protection, and disaster recovery by maintaining a synchronized copy of the primary database on a standby system. In this guide, we will configure Oracle 19c Active Data Guard between two Linux servers.

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1. Environment Setup

Primary Database: primary.localdomain (192.168.0.187)
Standby Database: standby.localdomain (192.168.0.188)

Update /etc/hosts on both servers:

192.168.0.187 primary.localdomain primary
192.168.0.188 standby.localdomain standby

Disable firewall & SELinux (if required):

systemctl stop firewalld
setenforce 0

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2. Enable FORCE LOGGING & ARCHIVELOG Mode on Primary

On the Primary Database:

ALTER DATABASE FORCE LOGGING;
ARCHIVE LOG LIST;

If not in ARCHIVELOG mode:

SHUTDOWN IMMEDIATE;
STARTUP MOUNT;
ALTER DATABASE ARCHIVELOG;
ALTER DATABASE OPEN;

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3. Configure Primary Initialization Parameters

Update the parameters using ALTER SYSTEM:

ALTER SYSTEM SET LOG_ARCHIVE_CONFIG='DG_CONFIG=(primary,standby)';
ALTER SYSTEM SET LOG_ARCHIVE_DEST_1='LOCATION=/u01/archive VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=primary';
ALTER SYSTEM SET LOG_ARCHIVE_DEST_2='SERVICE=standby ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=standby';
ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=ENABLE;
ALTER SYSTEM SET FAL_SERVER=standby;
ALTER SYSTEM SET FAL_CLIENT=primary;
ALTER SYSTEM SET DB_FILE_NAME_CONVERT='/u02/oradata/standby/','/u02/oradata/primary/';
ALTER SYSTEM SET LOG_FILE_NAME_CONVERT='/u02/oradata/standby/','/u02/oradata/primary/';
ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT=AUTO;

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4. Configure tnsnames.ora on Both Servers

Edit $ORACLE_HOME/network/admin/tnsnames.ora:

primary =
 (DESCRIPTION =
   (ADDRESS = (PROTOCOL = TCP)(HOST = primary.localdomain)(PORT = 1521))
   (CONNECT_DATA = (SERVICE_NAME = primary))
 )

standby =
 (DESCRIPTION =
   (ADDRESS = (PROTOCOL = TCP)(HOST = standby.localdomain)(PORT = 1521))
   (CONNECT_DATA = (SERVICE_NAME = standby))
 )

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5. Create Standby Redo Logs on Primary

Add standby redo logs (same size as primary redo logs, +1 group):

ALTER DATABASE ADD STANDBY LOGFILE GROUP 4 ('/u02/oradata/primary/standby_redo04.log') SIZE 500M;
ALTER DATABASE ADD STANDBY LOGFILE GROUP 5 ('/u02/oradata/primary/standby_redo05.log') SIZE 500M;
ALTER DATABASE ADD STANDBY LOGFILE GROUP 6 ('/u02/oradata/primary/standby_redo06.log') SIZE 500M;

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6. Create Password File & Transfer to Standby

On Primary:

orapwd file=$ORACLE_HOME/dbs/orapwprimary password=oracle entries=10 force=y
scp $ORACLE_HOME/dbs/orapwprimary oracle@standby:$ORACLE_HOME/dbs/orapwstandby

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7. Take RMAN Backup & Transfer to Standby

On Primary:

rman target /
RUN {
  BACKUP DATABASE PLUS ARCHIVELOG;
  BACKUP CURRENT CONTROLFILE FOR STANDBY FORMAT '/oradumps/standby_ctrl.bkp';
}
scp /oradumps/* oracle@standby:/oradumps/

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8. Restore Database on Standby

On Standby:

rman target /
STARTUP NOMOUNT;
RESTORE CONTROLFILE FROM '/oradumps/standby_ctrl.bkp';
ALTER DATABASE MOUNT;
CATALOG START WITH '/oradumps/';
RESTORE DATABASE;
RECOVER DATABASE;

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9. Configure Standby Initialization Parameters

Set parameters (reverse role values compared to primary):

ALTER SYSTEM SET DB_UNIQUE_NAME=standby;
ALTER SYSTEM SET LOG_ARCHIVE_CONFIG='DG_CONFIG=(primary,standby)';
ALTER SYSTEM SET LOG_ARCHIVE_DEST_1='LOCATION=/u01/archive VALID_FOR=(ALL_LOGFILES,ALL_ROLES) DB_UNIQUE_NAME=standby';
ALTER SYSTEM SET LOG_ARCHIVE_DEST_2='SERVICE=primary ASYNC VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=primary';
ALTER SYSTEM SET LOG_ARCHIVE_DEST_STATE_2=ENABLE;
ALTER SYSTEM SET FAL_SERVER=primary;
ALTER SYSTEM SET FAL_CLIENT=standby;
ALTER SYSTEM SET DB_FILE_NAME_CONVERT='/u02/oradata/primary/','/u02/oradata/standby/';
ALTER SYSTEM SET LOG_FILE_NAME_CONVERT='/u02/oradata/primary/','/u02/oradata/standby/';
ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT=AUTO;

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10. Start Managed Recovery

On Standby Database:

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;

For Active Data Guard (read-only + apply mode):

ALTER DATABASE OPEN;
ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE DISCONNECT FROM SESSION;

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11. Verify Configuration

Run these checks on both Primary and Standby:

SELECT DATABASE_ROLE, OPEN_MODE FROM V$DATABASE;
SELECT DEST_ID, STATUS, ERROR FROM V$ARCHIVE_DEST;

Expected output:

• Primary DB → PRIMARY, READ WRITE

• Standby DB → PHYSICAL STANDBY, READ ONLY WITH APPLY

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Conclusion

With this configuration, your Oracle 19c Active Data Guard environment is now up and running. Always validate in a test environment before production deployment. Active Data Guard ensures business continuity by providing real-time failover, load balancing for queries, and disaster recovery capabilities.

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