Patent ID: 8527700

Claim:
A management computer coupled to a storage apparatus that is accessed from an external device, the storage apparatus managing a pool that is provided with at least one real volume based on a RAID (Redundant Array of Independent (or Inexpensive) Disks) group, the management computer comprising: a storage resource; and a processor that is coupled to the storage resource, wherein the storage resource stores the pool management information, which includes a pool application information that indicates a pool application for the pool and an application condition information that indicates the condition for the pool application, and wherein the processor carries out the following processes (A) to (D): (A) calculating an excess storage capacity based on a pool usage status for the pool; (B) specifying a pool application for the pool and the condition for the pool application based on the pool management information; (C) judging whether the specified condition would be satisfied even if a storage area having a storage capacity equivalent to or less than the calculated excess storage capacity were to be deleted from the pool; and (D) defining a capacity equivalent to or less than the excess storage capacity as an unused capacity in the case in which the result of the judgment in the process (C) is positive.