Steps to Configure database in archive log mode in oracle

 SQL> select NAME,LOG_MODE from v$database;

  NAME      LOG_MODE
   ———       ————
    ORCL      NOARCHIVELOG

SQL> shutdown immediate;
 Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup mount
ORACLE instance started.

Total System Global Area  535662592 bytes
Fixed Size                  1375792 bytes
Variable Size             281018832 bytes
Database Buffers          247463936 bytes
Redo Buffers                5804032 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     15
Next log sequence to archive   17
Current log sequence           17
SQL> select name,log_mode from V$database;

NAME      LOG_MODE
--------- ------------
ORCL      ARCHIVELOG



database is configured in archive log mode.