select round(space_used/(1024*1024*1024),2) GBUsed,space_limit/(1024*1024*1024) MaxGB from v$recovery_file_dest

-- init parameter log_archive_dest_1 must be equal to LOCATION=USE_DB_RECOVERY_FILE_DEST
-- and db_recovery_file_dest must be set

select * from v$flash_recovery_area_usage