Patent ID: 8161303

Claim:
A storage apparatus comprising: a plurality of tray units each mounting a plurality of disk drives; and a controller configured to control access to the disk drives in response to an access request from a host apparatus, wherein the controller includes: a tray power management table in which standard power and a start-up power supply status are associated with each other for each of the tray units; an apparatus power table that manages the total power required by the tray units and present power consumed by the tray units; and a power setting table that defines the maximum available power relative to the total power and maximum number of trays which are powered on simultaneously, and wherein the controller is configured, responsive to receiving a power-on setting request for at least one tray unit of the tray units, to: calculate estimated power based on the standard power for the at least one tray unit and the present power, and total number of trays which are powered on, determine whether the estimated power is equal to or less than the maximum available power in the power setting table, and the total number of trays which are powered is equal to or less than the maximum number of trays which are powered on simultaneously in the power setting table, turn on the at least one tray unit when the estimated power is equal to or less than the maximum available power and the total number of trays which are powered on is equal to or less than the maximum number of trays which are powered on simultaneously, and then turn on one or more specified disk drives in the at least one tray unit without considering standard power of the specified disk drives, and send an error status when the estimated power is more than the maximum available power or the total number of trays which are powered on is more than the maximum number of trays which are powered on simultaneously.