A storage system comprises a plurality of hard disk drives and a storage controller providing a plurality of virtual volumes to a server and including a processor and a memory. The storage controller allocates pages of the plurality of virtual volumes to the plurality of hard disk drives in response to write requests. The storage controller controls to allocate outer sections of the plurality of hard disks to first addresses of the virtual volume and allocates inner sections of the plurality of hard disk drives to second addresses of the virtual volume, wherein the first addresses are lower than the second addresses.