A data storage apparatus includes a cache memory module and a NAND flash memory module including a cache memory mirror and a user data storage zone. The cache memory module is connected to the cache memory mirror via a path and electrically connected to the user data storage zone via another path. The cache memory module receives a write command that includes user data from a host, writes a copy of the user data into the user data storage zone in a write-back mode, and writes another copy of the user data cache memory mirror in a write-through mode. If some of the user data are lost from the cache memory module before they are written into the user data storage zone, the user data written in the cache memory mirror are copied and written into the cache memory module when the data storage apparatus is initiated again.