Use a storage system having a first data storage unit. The first data storage unit has a temporary storage area which is prepared in advance for the purpose of being provided to a host computer. Prior to completion of a process of creating a normal storage area within a second data storage unit in response to a storage area allocation request, the temporary storage area is associated with access point information for specifying access point in response to the allocation request. The access point information is to be used by the host computer to access the normal storage area. Then prior to completion of the normal storage area creation process, an access by an access request including the access point information from the host computer is relayed to the temporary storage area associated with the access point information.