Patent ID: 7257722

Claim:
A storage system, comprising: a channel adapter coupled to a host computer and receiving a read/write command sent from said host computer; a memory coupled to said channel adapter and storing data transferred from said channel adapter; a disk adapter coupled to said memory and transferring data stored in said memory to a plurality of storage regions; a plurality of disk drive units having said storage regions and storing data transferred from said disk adapter; at least one Direct Current (DC) power supply device supplying DC power to at least one load, said load having said channel adapter, said memory, said disk adapter or said disk drive units; and at least three Alternate Current (AC) units having at least one breaker, said breaker interrupting supply of AC power if the AC power exceeds a certain level, and receiving AC power supplied from outside and supplying AC power to said DC power supply device, wherein a total of AC power supplied from said AC units is less than an amount of twice DC power consumption of said load.