Patent ID: 8868878

Claim:
A disk array system coupled to a host computer, comprising: a plurality of hard disk drives; an expander device including a memory and a plurality of ports, each port coupled to one of the plurality of hard disk drives; and a disk controller being coupled to the expander device and controlling data transfer between the host computer and the plurality of hard disk drives via the expander device, wherein each of the plurality of hard disk drives stores its own particular parameter information used for communication with the expander, wherein, when the disk controller begins communication between the disk controller and a first disk drive coupled to a first port of the plurality of ports of the expander via the expander, the disk controller is configured to: read first particular parameter information, which comprises a plurality of parameter values being suited for the communication between the expander and the first disk drive regarding an attribute of the first disk drive, from the first disk drive via the expander; specify a first particular parameter value, which is suitable for the communication between the expander and the first disk drive based on a location to which the first disk drive is mounted from among the plurality of parameter values of the first particular parameter information; and set the first particular parameter value on a memory of the first port of the expander and on the first disk drive so that the expander and the first disk drive can optimize a status of communication between the expander and the first disk drive based on the first particular parameter value, wherein the first disk drive is capable of changing operating modes, wherein before the first particular parameter value is set on the memory of the first port of the expander and on the first disk drive, the first disk drive is operated in a first operation mode in which the first disk drive communicates with the expander at a first speed rate, and wherein after the first particular parameter value is set on the memory of the first port of the expander and on the first disk drive, the first disk drive is operated in a second operation mode in which the first disk drive communicates with expander at a second speed rate which is faster than the first speed rate.