A data storage device is provided. The data storage device includes: a first function block of a device controller configured to receive user data and perform a first data processing; a first buffer memory connected to the first function block and configured to store user data subjected to the first data processing as first process data; a second function block of the device controller configured to receive a data write command determined based on the first process data; and a non-volatile memory connected to the second function block, and configured to receive and store data stored in the first buffer memory. The user data is provided to the first function block before the data write command is provided to the second function block.