Patent ID: 7979639

Claim:
A storage apparatus comprising: a storage control device; and a storage drive device that is connected to the storage control device, wherein the storage control device includes: a central processing unit that performs overall control of the storage apparatus; a memory that stores a program or data needed by the central processing unit for controlling the storage apparatus; and a cache memory that is used for having a local unit (LU), which is a logical space for data access of a host computer using the storage apparatus, to be resident, wherein the storage drive device includes a plurality of storage devices, wherein the LU that is resident in the cache memory is configured by a set of pages acquired by dividing a pool volume as a physical space created by using the plurality of storage devices in a predetermined size, and wherein, in the memory, a program is executed by the central processing unit and is used for a cache-residence process in which, when the LU to be resident in the cache memory is created, a capacity corresponding to the size of the LU is not initially acquired in the cache memory, a cache capacity that is the same as the physical capacity allocated to a new page is acquired in the cache memory each time when the page is newly allocated, and the new page is resident in the cache memory is stored.