RMAN BACKUP AND RECOVERY BASIC

RMAN-03009: failure of backup command on ORA_DISK_1 
ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode

This message indicates that before you can create an RMAN online backup, you need to
place your database into archivelog mode.

SQL> archive log list;
Database log mode              No Archive Mode
Automatic archival             Disabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     19
Current log sequence           21
SQL> select log_mode from v$database;

LOG_MODE
------------
NOARCHIVELOG

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.

Total System Global Area  444596224 bytes
Fixed Size                  1219904 bytes
Variable Size             138412736 bytes
Database Buffers          301989888 bytes
Redo Buffers                2973696 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     19
Next log sequence to archive   21
Current log sequence           21
SQL> select log_mode from v$database;

LOG_MODE
------------
ARCHIVELOG

now try rman backup

[oracle@rac1 ~]$ rman target /

connected to target database: JAY (DBID=3148849783)

RMAN> backup database;