oracle archive problem

--Query log
select * from v$recovery_file_dest;
select sum(percent_space_used)*3/100 from v$flash_recovery_area_usage;
select * from v$flash_recovery_area_usage;
select * from v$version;

-- so enter the rman program to delete the archived log
rman target sys/pass@prjdb
crosscheck archivelog all;
delete archivelog until time 'sysdate'; --delete all logs
delete expired archivelog all;--delete expired logs

--the maximum archive log directory at this time becomes 20G. Restart oralce again with this setting.
SQL> alter system set db_recovery_file_dest_size=21474836480;---Set the size of the space used (20*1024*1024*1024), 20GB
System altered
SQL> show parameter db_recovery_file_dest;---View the archive log path limit