Patent ID: 7437576

Claim:
A power management apparatus, for managing the quantity of power that is consumed by a computer group including a plurality of computers interconnected by a network, comprising: controllers, provided for the computers, for respectively obtaining a quantity of power consumed by each of the computers in the computer group; storage units, provided for the computers, for storing a maximum quantity of power to be supplied to the computer group; and an overall controller for obtaining, from the controllers of the computers, the quantities of power consumed by the computers and for adjusting power consumption so that a total value of a power consumed by the computer group is not greater than the maximum quantity of power, wherein the overall controller is activated by one computer in the computer group, wherein, operating mode information, indicating a plurality of operating modes corresponding to power consumption for the computers, and setup information, indicating operating modes currently set for the computers, are also stored in the storage units, and wherein, based on the operating mode information and the setup information, the overall controller adjusts the total quantity of power consumed by the computer group so as not to exceed the maximum quantity of power, wherein the operating mode information stored in the storage units includes data for the maximum power consumption and for a number of transactions for each of the operating modes for each of the computers, and wherein each of the controllers includes: a unit for obtaining from the corresponding computer, for each predetermined time, information concerning the number of transactions; a determination unit for examining the operating mode information to obtain the number of transactions that corresponds to an operating mode currently set for the corresponding computer, for comparing the number of transactions with the number of transactions obtained from the operating mode information, and for determining whether the operating mode currently set for the corresponding computer is appropriate and a unit for employing the determination results obtained by the determination unit to transmit an operating mode change request to the overall controller.