Habilitar/Desabilitar Archivelog no banco de dados Oracle

Habilitando...
SQL> select log_mode from gv$database;
SQL> shutdown immediate;
SQL> startup mount exclusive;
SQL> alter database archivelog;
SQL> alter database open;
SQL> select log_mode from gv$database;

Desabilitando...
SQL> startup mount
SQL> alter database noarchivelog;
SQL> alter database open;