1. A storage apparatus comprising: one or more storage drives for providing real storage resources; and a controller configured to control the one or more storage drives and accesses from a host computer, wherein the controller is configured to initialize real storage resources and to include management information for managing the initialized real storage resources; wherein the controller is configured to receive an instruction for allocating an initialized real storage resource to a first virtual storage resource accessed by the host computer; wherein, in response to the instruction, the controller is configured to receive a determination whether unallocated initialized real storage resources exist with reference to the management information; and wherein, when the determination is positive, the controller is configured to allocate a first initialized real storage resource selected from the management information to the first virtual storage resource without further initializing the selected first initialized real storage resource.