Some days ago I went into this error while trying to perform a backup of a running 11gR2 database using rman:
ORA-196602: cannot backup or copy active file in NOARCHIVELOG mode
The solution was easy: ArchiveLog needs to be enabled to perform a hot backup of a running database.
Using SQLPlus connect to database.
[oracle@orcl ~]$ /u01/app/oracle/product/11.2.0/db_1/bin/sqlplus sys/password as sysdba
SQL*Plus: Release 220.127.116.11.0 Production on Tue Jul 10 09:32:39 2012
Copyright (c) 1982, 2011, Oracle. All rights reserved.
Oracle Database 11g Release 18.104.22.168.0 - 64bit Production
Stop and dismount database and shutdown instance.
SQL> shutdown immediate;
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 1653518336 bytes
Fixed Size 2228904 bytes
Variable Size 1325403480 bytes
Database Buffers 318767104 bytes
Redo Buffers 7118848 bytes
SQL> alter database archivelog;
SQL> alter database open;
If everything went fine the following command should return Archive Mode as output:
SQL> select log_mode from v$database;
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence 294
Next log sequence to archive 296
Current log sequence 296