Patent ID: 8909883
Filing Date: 2014-12-09
Classification: G06F

Abstract:
1. A storage system communicably coupled to a host computer, the storage system comprising: a plurality of storage media; a memory region; a cache memory region; and a processor, wherein the plurality of storage media configures a pool having a plurality of pages, wherein the pool configured a plurality of logical volumes including a primary volume and at least one secondary volume, the primary volume is configured by a plurality of logical regions where data of the host computer is stored, and the at least one secondary volume is a logical volume configured by a plurality of virtual regions for holding at least one snapshot image of the primary volume corresponding to at least one snapshot acquisition point of time of the primary volume, wherein, in the case in which a virtual region of a write destination of data is not allocated to a page in the pool, a page is allocated to the virtual region of the write destination and the data is stored into the page allocated to the virtual region, wherein the cache memory region stores at least one data element that is to be written to one of the logical regions of the primary volume, wherein the memory region stores time relation information that indicates a time relationship of each data element that has been stored in logical regions of the primary volume and each data element that has been stored into the cache memory region and that is to be written to one of the logical regions and the at least one snapshot acquisition point of time of the primary volume, wherein the processor is configured to: (A) receive a write request from the host computer to the primary volume specifying a write destination of the primary volume, (B) judge whether or not a first data element that has been previously stored into the cache memory region and that is to be written to a logical region as the write destination of the primary volume corresponding to the write request is a snapshot configuration element that configures a snapshot image of the primary volume based on the time relation information for the first data element, (C) in the case in which the first data element is a snapshot configuration element, identify the time relation information corresponding to a data element stored in the logical region of the write destination of the first data element, save the snapshot configuration element in the cache memory region to the secondary volume for holding a snapshot image to which the snapshot configuration element belongs, and then store a second data element of the write request in the cache memory region, and (D) in the case in which the first data element is not a snapshot configuration element, store a second data element of the write request in the cache memory region wherein in (C), the processor is configured to identify a secondary volume holding the snapshot image of the logical region of the write destination of the first data element corresponding to a different time relation information than the identified time relation information, allocate a page from the pool to the virtual region of the second volume identified, and store the data element stored in the logical region of the write destination of the first data element into the page allocated.