Patent ID: 6915382

Claim:
A storage system comprising: at least two physical disk devices storing data of a plurality of logical disk devices, wherein a logical disk device is a target device of an access request from a data processing unit coupled to the storage system; a controller, coupled to the data processing unit, for controlling data accesses from the data processing unit, wherein said controller performs the steps of: referring to access information about access activity to said logical disk devices in said at least two physical disk devices, determining, in accordance with said access information about access activity, a first logical disk device allocated in at least one first physical disk device having a first access activity and a second logical disk device allocated in at least one second physical disk device having a second access activity, wherein said first access activity is greater than said second access activity, transferring said first logical disk device from said at least one first physical disk device to said at least one second physical disk device and transferring said second logical disk device from said at least one second physical disk device to said at least one first physical disk device, and updating correlation between logical disk devices and physical disk devices.