DEVICE AND METHOD FOR BUFFER CONTROL OVER DISK UNIT

PROBLEM TO BE SOLVED: To adjust the reconnection timing to be optimum according to the difference between the data transfer speed of an SCSI interface side (host side) and the data transfer speed of a disk interface side (drive side) at the time of writing. SOLUTION: A reconnection timing control part 3 when receiving a write command analyzes SCSI protocol data by using a host transfer speed analyzing means 31 and estimates a host data transfer speed from the data by a host transfer speed calculating means 32. Similarly, the physical position of a disk is calculated from the logical address data of the write command by using an address logical/physical converting means 33 and a disk transfer speed corresponding to the position is estimated by a disk transfer speed calculating means 34. The best buffer data ratio for reconnection is found from the two transfer speeds by using an optimum ratio determining means 35. Consequently, a proper reconnection is made and optimum data transfer is performed.