Patent ID: 7667918

Claim:
A disk array device having a plurality of hard disk drives for respectively storing data, and which converts a first direct voltage supplied to each of said hard disk drives via a common power supply bus into a second direct voltage required by said hard disk drives at each of said hard disk drives, wherein each of said hard disk drives comprises: a voltage converter for converting said first direct voltage into said second direct voltage; a control unit for controlling said voltage converter so as to suppress the fluctuation of said second direct voltage based on said second direct voltage output from said voltage converter; and a response characteristics switching unit for switching the response characteristics of said control unit against the fluctuation of said second direct voltage so as to improve said response characteristics of said control unit against the fluctuation of said second direct voltage when a transitional voltage fluctuation of said second direct voltage occurs; wherein said voltage converter converts said first direct voltage into a plurality of types of mutually differing second direct voltages, and wherein said control circuit includes an adjustment unit for adjusting the degree of controlling each of said second direct voltages, and said control unit controls said voltage converter so as to suppress the fluctuation of each of said second direct voltages based on the degree of control adjusted with said adjustment unit.