A data processing method including: searching for a smallest data unit of a buffer with regard to appending data in an append write request; sequentially writing at least some of the appending data into the smallest data unit of the buffer to obtain a first smallest data unit to be stored, and writing data not yet written in the appending data into at least one smallest data unit to obtain at least one second smallest data unit to be stored; writing the first smallest data unit to be stored into a storage device in an overwriting manner, and sequentially writing the at least one second smallest data unit to be stored into the storage device; and buffering a smallest data unit not fully written that corresponds to the appending data. The present disclosure ensures data integrity, increase operation convenience, and write operation efficiency.