To enable Archive Log Mode in an Oracle 19c RAC database.

Step 1: Check Current Archive Log Mode Status

Before changing the Archive Log mode, check the current status of the database.

select log_mode, name from v$database;

LOG_MODE    NAME
----------  --------
NOARCHIVELOG EKONE

archive log list;

Database log mode              No Archive Mode
Automatic archival             Disabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence      4
Current log sequence            5
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exit

The database is currently in NOARCHIVELOG mode, and automatic archival is disabled.

Step 2: Stop the RAC Database Service

Stop the database service before making changes.

[oracle@rac1 ~]$ srvctl stop database -d EKONE
[oracle@rac1 ~]$ srvctl status database -d EKONE

Instance EKONE1 is not running on node rac1
Instance EKONE2 is not running on node rac2

Step 3: Start the RAC Database in Mount State

Start the database in mount state to make the changes.

[oracle@rac1 ~]$ srvctl start database -d EKONE -o mount
[oracle@rac1 ~]$ srvctl status database -d EKONE

Instance EKONE1 is running on node rac1
Instance EKONE2 is running on node rac2

Step 4: Enable Archive Log Mode and Set Archive Destination

Now, connect to the database as sysdba and enable the ARCHIVELOG mode, setting the archive destination to an ASM disk group.

[oracle@rac1 ~]$ sqlplus / as sysdba

SQL> alter system set log_archive_dest_1='LOCATION=+DATA/' scope=both sid='*';

System altered.

SQL> alter database archivelog;

Database altered.

Step 5: Stop the RAC Database Service

After enabling ARCHIVELOG mode, stop the database service again.

[oracle@rac1 ~]$ srvctl stop database -d EKONE

Step 6: Restart the RAC Database

Restart the RAC database to apply the changes.

[oracle@rac1 ~]$ srvctl start database -d EKONE
[oracle@rac1 ~]$ srvctl status database -d EKONE

Instance EKONE1 is running on node rac1
Instance EKONE2 is running on node rac2

Step 7: Verify Archive Log Mode

Check if the ARCHIVELOG mode has been enabled successfully.

SQL> archive log list;

Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            +DATA
Oldest online log sequence      4
Next log sequence to archive    5
Current log sequence            5

SQL> select log_mode, name from v$database;

LOG_MODE    NAME
----------  --------
ARCHIVELOG  EKONE

The database is now in ARCHIVELOG mode, with automatic archival enabled and the archive destination set to the ASM disk group.

By following these steps, you've successfully enabled Archive Log mode in your Oracle 19c RAC database. This change helps ensure that your database logs are archived, which is crucial for point-in-time recovery.