Patent ID: 8935488
Filing Date: 2015-01-13
Classification: G06F

Abstract:
1. A storage system that is coupled to a host computer in such a manner that the storage system can communicate with the host computer, comprising: a plurality of storage devices that are a basis of a pool and a primary volume; and a controller that is coupled to the plurality of storage devices and the host computer and that is provided with a cache region, wherein the pool is configured by a plurality of pages, wherein the controller generates a secondary volume that is a snapshot of the primary volume, wherein the primary volume is a logical volume that is configured by a plurality of logical regions in which data that is used for a processing of the host computer is stored, wherein the secondary volume is a virtual logical volume that is configured by a plurality of virtual regions for holding a snapshot image of the primary volume, wherein (A) in the case in which the controller receives a write request that specifies the secondary volume from the host computer, wherein (B) in the case in which a page in the pool is unallocated to a virtual region of a write destination of the write data, wherein, the controller writes a data part in a logical region that corresponds to the virtual region of the write destination to an area of the first cache sub region other than an area of the write data in the first cache sub region in the (b1), and the data that is written to a page in the (b2) is data that includes the write data and the data part.