A data storage system includes a non-volatile memory, a disc recording medium, a non-volatile memory buffer, operatively disposed between a host interface and the non-volatile memory, which stores a portion of data stored in the non-volatile memory, and a disc buffer, operatively disposed between the host interface and the disc recording medium, which stores a portion of data stored in the disc recording medium. The data storage system may be configured to receive an access address from a host operatively connected to the host interface, and sequentially determine whether the access address exists in one of the non-volatile memory buffer, the non-volatile memory, the disc buffer, and the disc recording medium, in that order.