Patent ID: 7945732
Filing Date: 2011-05-17
Classification: G06F

Abstract:
1. A storage system, comprising: a plurality of physical storage devices; a plurality of logical volumes formed based on a storage area group that constitutes the storage space of the plurality of physical storage devices; an access module that performs access, based on a RAID level corresponding to the logical volume, to each of the storage areas of each of two or more physical storage devices that constitute an access destination logical volume; a load calculation module that calculates the load of each of the physical storage devices based on a load that accompanies the access to each storage area; and a load distribution processing module which executes load distribution processing to distribute the loads of the plurality of physical storage devices and which comprises a judgment module and a data re-arrangement module, wherein, in the load distribution processing, the judgment module selects one storage area from two or more storage areas of a high load physical storage device, selects a physical storage device with a lower load than that of the physical storage device, and makes a judgment of whether the redundancy according to the RAID level decreases when data elements stored in the selected storage area are transferred to the selected low load physical storage device, wherein when a result of the judgment is that the redundancy does not decrease, the data re-arrangement module transfers the data elements stored in the selected storage area to a buffer area of the selected low load physical storage device, which is a storage area used as a buffer that does not correspond to a logical address space of the logical volume, and associates the logical address space of the logical volume that corresponds to the selected storage area with the buffer area, and wherein when a result of the judgment is that the redundancy decreases, the judgment module selects a physical storage device which has a lower load than the load of the high load physical storage device, and has a higher load than the physical storage device selected in the previous judgment.