ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode

-bash-3.00$ rman
RMAN> connect target /
connected to target database: ORCL(DBID=2560365586)
RMAN> backup database;
Starting backup at 27-DEC-10
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=59 device type=DISK
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
RMAN-03009: failure of backup command on ORA_DISK_1 channel at 12/27/2010 09:21:13
ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode
continuing other job steps, job failed will not be re-run
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
including current control file in backup set
including current SPFILE in backup set
channel ORA_DISK_1: starting piece 1 at 27-DEC-10
channel ORA_DISK_1: finished piece 1 at 27-DEC-10
piece handle=/u01/app/oracle/flash_recovery_area/ORCL/

backupset/2011_12_27/o1_mf_ncsnf_TAG20111227T092110_7hlwhbss_.bkp tag=TAG20111227T092110 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================

RMAN-03009: failure of backup command on ORA_DISK_1 channel at 12/27/2010 09:21:13
ORA-19602: cannot backup or copy active file in NOARCHIVELOG mode

To be able to take a hotbackup with RMAN, you have to enable ARCHIVELOG MODE.
 

To see how to enable ARCHIVELOG MODE, How to enable ARCHIVELOG MODE

To enable archivelog mode, user must have sysdba privileges.

SQL> connect sys/solarishowto as sysdba

SQL> shutdown immediate;
SQL> startup mount;
SQL> alter database archivelog;
SQL> alter database open;
Lets check that archivelog mode is enabled
SQL> select log_mode from v$database;
LOG_MODE
——————–
ARCHIVELOG