Patent ID: 8645750

Claim:
A computer system comprising a storage apparatus that allocates a real storage area from a plurality of real storage areas of a plurality of storage devices according to an access from a host computer, the storage apparatus comprising: a virtual logical area having a plurality of virtual volumes to be provided to the host computer; a plurality of real logical areas including the real storage areas, a controller for controlling the allocation of the real storage area from the real logical areas to the virtual logical area; and at least one pool comprised of the plurality of real logical areas, wherein the controller assigns the pool to the virtual volumes, and the controller assigns pages to the virtual volumes from the real logical areas, wherein the controller: detects an event that occurs in one of the real logical areas; controls the allocation of the real storage areas from the real logical areas to the virtual logical area based on the event, stops assignment of pages to the virtual volumes from the real logical area where the event occurred, removes the real logical area from the corresponding pool, if the controller determines that the real logical area where the event occurred needs to be removed; adds another real logical area to the corresponding pool, if the controller determines another real logical area should be added to the corresponding pool; wherein the controller further: allocates real storage areas from the real logical areas to an impact range of the virtual volume; seeks a scheduled time of recovery from the event and an access interval from the host computer to each of the plurality of real storage areas; decides a priority for migrating the data to the other real logical areas between the plurality of real storage areas based on the scheduled time of recovery and the access interval, and migrates the data from the real storage areas to the other real logical areas based on the priority; wherein if the type of the event is operation of the real logical area according to a degenerate mode based on the occurrence of a failure in at least one of the storage devices configuring the real logical area subject to the event, compares a first performance of the real logical area subject to the event and a second performance of the virtual logical area; wherein if the first performance falls below the second performance, migrates data of the real storage area that was allocated to the virtual logical area within the real logical area subject to the event to another of the real logical areas with a performance that is higher than the performance of the virtual logical area; wherein if the type of the event is operation of stopping the real logical area, excludes the real logical area from allocating the real storage areas thereof to the virtual logical area.