Patent ID: 9448733
Filing Date: 2016-09-20
CPC Classification: G06F

Claim Text:
1. A storage system coupled to an external storage system, the storage system comprising: a plurality of internal storage devices; a control unit configured to manage a virtual volume including a plurality of virtual storage areas, and manage a first pool including a plurality of first real storage areas formed by the plurality of internal storage devices and a second pool including a plurality of second real storage areas provided by the external storage system, the second pool being managed as lower performance than the first pool, and wherein the control unit is configured to: allocate a first real storage area of the first pool to a first virtual storage area in the virtual volume for storing data related to a first write request to the first virtual storage area, allocate a second real storage area of the second pool to a second virtual storage area in the virtual volume for storing data related to a second write request to the second virtual storage area, and allocate a third real storage area of the second pool to the first virtual storage area of the virtual volume, on the basis of an access frequency of the data related to the first virtual storage area, so that the data stored in the first real storage area is migrated to the third real storage area of the second pool.