Patent ID: 7707381

Claim:
A storage system comprising: a plurality of nodes, at least one of the nodes including a storage having a physical volume, the storage mapping logical extents that compose a logical volume in physical extents of the physical volume and storing the logical extents in the physical volume; and an interface which connects the nodes and a host, wherein: at least two of the nodes include controllers which provide the host with the logical volume and receive access from the host; said at least one of the nodes or at least another one of the nodes includes a management server which performs a location management service to reply to an inquiry about a location of a storage that stores the logical extents of the logical volume from any of the controllers; each of the controllers includes a first mapping table indicating a management server corresponding to the logical extents of the logical volume; the management server included in said at least one of the nodes includes a second mapping table indicating which node includes a storage that stores logical extents corresponding to the management server included in said at least one of the nodes; the storage included in said at least one of the nodes includes a third mapping table indicating which physical extents of the physical volume included in the storage included in said at least one of the nodes store the logical extents; when each of the controllers receives an access request that designates a logical extent in the logical volume as an access destination from the host, said each of the controllers refers to its corresponding first mapping table to specify a management server corresponding to the designated logical extent, and inquires of the specified management server which storage stores the designated logical extent; when the specified management server receives an inquiry from one of the controllers, the specified management server refers to the second mapping table to specify the inquired storage which stores the designated logical extent, and notifies said one of the controllers, which is an inquiry source, of information indicating the inquired storage which stores the designated logical extent as a reply to the inquiry; each of the controllers requests the storage indicated by the information as a reply to the inquiry to gain access to the logical extent designated by the host; and when one of the controllers requests the storage indicated by the information to gain access to a logical extent, the storage indicated by the information refers to the third mapping table to specify a physical extent corresponding to the designated logical extent in the physical volume, gains access to the specified physical extent, and replies to said one of the controllers which is an access request source.