An efficient data storage device is disclosed, which uses a microprocessor and at least one volatile memory to operate a non-volatile memory. The microprocessor allocates the volatile memory to provide a cache area. According to an asynchronous event request (AER) issued by a host, the microprocessor uses the cache area to collect sections of write data requested by the host, programs the sections of write data collected in the cache area to the non-volatile memory together, and reports failed programming of the sections of write data to the host by AER completion information.