Patent ID: 8688909

Claim:
A storage apparatus connected via a network to a host computer which requests data writing, comprising: storage devices of a plurality of types of varying performance; and a controller which manages storage areas provided by each of the storage devices of a plurality of types by means of storage tiers of a plurality of different types, and which assigns the storage areas in page units to virtual volumes from any of the storage tiers among the storage tiers of the plurality of types according to the data write request from the host computer, wherein the controller monitors performance information which includes I/O characteristic information for each of the virtual volumes and determines the storage tiers corresponding to the performance information thus monitored, and assigns the storage areas in page units to the virtual volumes from the determined storage tiers, wherein the controller monitors performance information which includes I/O characteristic information for predetermined areas of the virtual volumes and determines the storage tiers corresponding to the performance information thus monitored for each of the predetermined areas of the virtual volumes, and assigns the storage areas in page units to the predetermined areas of the virtual volumes from the determined storage tiers, and wherein the controller assigns storage areas in page units from the storage tiers determined for the predetermined areas of the virtual volumes and calculates an assignment ratio of the storage tiers assigned to each of the virtual volumes.