RAC 11.2 enable archivelog

[oracle@rac1 ~]$ sqlplus / as sysdba
SQL> show parameter recovery;

NAME                     TYPE     VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest             string
db_recovery_file_dest_size         big integer 0
recovery_parallelism             integer     0

SQL> alter system set db_recovery_file_dest_size=20G scope=both sid='*';
SQL> alter system set db_recovery_file_dest='+FRA' scope=both sid='*';
SQL> archive log list;
Database log mode           No Archive Mode
Automatic archival           Disabled
Archive destination           USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     4
Current log sequence           5
SQL> alter system set cluster_database=false scope=spfile sid='racdb1';
SQL> exit
[oracle@rac1 ~]$ srvctl stop database -d racdb
[oracle@rac1 ~]$ sqlplus / as sysdba

SQL> startup mount
SQL> alter database archivelog;
SQL> alter system set cluster_database=true scope=spfile sid='racdb1';
SQL> shutdown immediate
SQL> exit
[oracle@rac1 ~]$ srvctl start database -d racdb
[oracle@rac1 ~]$ sqlplus / as sysdba
SQL> archive log list;
Database log mode           Archive Mode
Automatic archival           Enabled
Archive destination           USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     4
Next log sequence to archive   5
Current log sequence           5