Patent ID: 7996612

Claim:
A computer system, comprising: a computer; and a storage system coupled to the computer through a network, wherein: the computer has an interface, which is coupled to the network, a processor, which is coupled to the interface, and a memory, which is coupled to the processor; the storage system has a plurality of disk drives and a controller, which controls the plurality of disk drives; the plurality of disk drives provide a data storage area that is partitioned into a plurality of logical volumes; the plurality of logical volumes include a first number of first logical volumes and as many second logical volumes as the first number; each of the plurality of logical volumes belongs to one of a plurality of volume sets; the plurality of volume sets include a first volume set to which the first number of the first logical volumes belong and a second volume set to which the first number of the second logical volumes belong; the first number of the first logical volumes are allocated dispersedly to a second number of the disk drives; the first number of second logical volumes are allocated dispersedly to a third number of the disk drives, the third number being larger than the second number; and the computer holds management information which associates each of the first logical volumes and each of the second logical volumes with each other, and is configured to: select one of the first volume set and the second volume set based on a result of judging whether or not a predetermined condition is met; store data of a file dispersedly in the first number of the logical volumes belonging to the selected volume set; and send an instruction to the storage system to stop spinning of disks in the disk drives to which none of the first number of the logical volumes belonging to the selected volume set are allocated.