if st.dbs[dn] != :safecopy_flushed
            return send_data("CLIENT_ERROR storage[#{dn}] != :safecopy_flushed status\r\n")
          end
          if st.set_db_stat(dn, :cachecleaning) == false
            return send_data("CLIENT_ERROR storage[#{dn}] status can't changed\r\n")