How to Enable Archive Log Mode in Oracle Database (ASM)

Check if the Archivelog mode is enabled

SQL> archive log list;

Database log mode              No Archive Mode

Automatic archival             Disabled

Archive destination            ?#/dbs/arch

Oldest online log sequence     4146

Current log sequence           4148

SQL> select log_mode from v$database;

LOG_MODE

------------

NOARCHIVELOG

Enable Archive log mode using Flash Recovery Area

How to Enable Flash Recovery Area

To enable Flash Recovery Area you need to set db_recovery_file_dest_size and db_recovery_file_dest parameter.

SQL> show parameter db_recovery_file_dest

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

db_recovery_file_dest                string

db_recovery_file_dest_size           big integer 0

SQL> alter system set db_recovery_file_dest_size=50G scope=both;

System altered.

SQL> alter system set db_recovery_file_dest='+DG_TST_FRA' scope=both;

System altered.

SQL> show parameter db_recovery_file

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

db_recovery_file_dest                string      +DG_TST_FRA

db_recovery_file_dest_size           big integer 50G

SQL> archive log list;

Database log mode              No Archive Mode

Automatic archival             Disabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     4146

Current log sequence           4148

NOTE:As soon as you enable the FRA the archiving location is implicitly set to FRA even if the Archivelog mode is not enabled

Put the database in mount mode and enable the achivelog mode

SQL> shut immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup mount;

ORACLE instance started.

Total System Global Area 2147483648 bytes

Fixed Size                  8794848 bytes

Variable Size            1912605984 bytes

Database Buffers          218103808 bytes

Redo Buffers                7979008 bytes

Database mounted.

SQL> alter database archivelog;

Database altered.

SQL> alter database open;

Database altered.

SQL> archive log list;

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     4146

Next log sequence to archive   4148

Current log sequence           4148

If you don't want to use FRA you can instruct oracle to write the logs on some other location by setting log_archive_dest_ parameter.