Patent ID: 8489813
Filing Date: 2013-07-16
Classification: G06F

Abstract:
1. A storage system, comprising: a plurality of flash memory devices; and a controller configuring a plurality of logical volumes formed based on a storage area group that constitutes a storage space of the plurality of flash memory devices, wherein the controller performs access, based on a RAID (Redundant Array of Independent (or Inexpensive) Disks) level corresponding to a logical volume, to each storage area of each of two or more flash memory devices that constitute the logical volume, wherein the controller calculates a load of each of the flash memory devices based on a load that accompanies the access to each storage area, wherein the controller determines whether a difference of any of two loads among the calculated load of each of the flash memory devices is above a predetermined value, wherein when it is determined that the difference of any of two loads is above a predetermined value, the controller executes load distribution processing to distribute the loads of the plurality of flash memory devices, wherein, in the load distribution processing, the controller selects a high load flash memory device and selects a high load first storage area from two or more storage areas of the selected high load flash memory device, selects a flash memory device with a lower load than the load of the selected high load flash memory device, selects a low load second storage area from two or more storage areas of the selected low load flash memory device, wherein the controller makes a determination of whether the redundancy according to the RAID level decreases when data elements stored in the first storage area are transferred to the selected low load flash memory device, wherein when a result of the determination is that the redundancy does not decrease, the controller executes replacement processing between the data elements stored in the first storage area and data elements stored in the second storage area, wherein when a result of the determination is that the redundancy decreases, the controller selects another flash memory device which has a lower load than the load of the selected high load flash memory device, and has a higher load than the load of the selected low load flash memory device, and wherein the controller levels loads of the plurality of flash memory devices by executing the load distribution processing more than once.