Patent ID: 8453011

Claim:
A storage system comprising: a first storage system including a first logical volume, comprised of a thin provisioning volume, where a first data area is dynamically allocated to prescribed areas, and a first controller which stores data transmitted from a host computer in said first data area, and a backup server, which does not include a thin provisioning volume, having a second data area for backing up said first logical volume; wherein said first controller: manages the status of said first data area allocated to each of said prescribed areas of said first logical volume; transfers said data stored in said first data area allocated to each of said prescribed areas of said first logical volume and allocation information which indicates allocated area in said first logical volume to said backup server; and restores said first logical volume based on the status of said first data area; wherein said first controller includes a first allocation unit for allocating, upon restoring said first logical volume, said first data area to an area of said first logical volume with said first data area in existence, and restores said first logical volume by writing said data transferred from said back-up server in said first data area allocated by said first allocation unit; wherein said first allocation unit, upon restoring said first logical volume, releases all said first data areas allocated to each of said prescribed areas of said first logical volume, and newly allocates said first data area to said area of said first logical volume with said first data area in existence.