Patent ID: 7155567

Claim:
A control method for a data transfer device that comprises a data receiver for receiving write data to be stored in a disk drive; a data control unit for transferring in block units the write data received by the data receiver to the disk drive; and data storage unit for temporarily storing serial data that is read from a storage area of the disk drive, wherein the method is performed by the data control unit and comprises the steps of: reading the serial data from the disk drive in block units and temporarily storing this serial data in block units in the data storage unit; comparing a logical block address of a write destination of the received write data with a logical block address of the serial data read from the disk drive and temporarily stored in the date storage unit; when the logical block address of the write destination of the received write data is the same as the logical block address of the serial data read from the disk drive and temporarily stored in the data storage unit compared therewith, updating the serial data temporarily stored in the data storage unit by means of the received write data so that the updated serial data is available to be compared to the next-received write data; and when the logical block address of the write destination of the received write data is different from the logical block address of the serial data read from the disk drive and temporarily stored in the data storage unit compared therewith, generating a security code based on the serial data temporarily stored in the data storage unit and according to the order of storage areas of the disk drive, adding the generated security code to the serial data temporarily stored in the data storage unit, transferring in block units this serial data having the security code added thereto to the disk drive, reading the serial data stored in the block in the disk drive constituting the write destination of the received write data, and updating the serial data thus read and stored in the data storage unit by means of the write data so that the updated serial data is available to be compared to the next-received write data.