Patent ID: 9329788
Filing Date: 2016-05-03
CPC Classification: G06F

Claim Text:
1. A storage system comprising: a virtual volume which is a virtual logical volume, commutatively connected to one or more access sources and includes one or more multiple virtual pages; a pool that includes one or more real pages, wherein each real page includes one or more real regions; and a storage controller configured to: receive a write command that contains target data and designates a write destination virtual address for one or more of the access sources, allocate an unallocated real page as an allocated real page to a write destination virtual page located at the write destination virtual address, when the real page is not allocated to the write destination virtual page located at the write destination virtual address, and write the target data to a real region in the allocated real page, receive a special write command, that includes a command for writing predetermined data and designates a write destination address, write the predetermined data, in response to the special write command, to a real region corresponding to the write destination address, perform data move processing, when a number of recoverable real pages is more than a second threshold value, for moving all valid data stored in two or more move-source real pages respectively allocated to two or more virtual pages, to move-destination real pages the number of which is less than a number of move-source real pages in units of real regions, each piece of valid data being data that can be used by any one of the one or more access sources, write the predetermined data to all move-source real regions in each of move-source real pages, so that each of the move-source real pages is set as a recovery target real page which is a real page storing only the predetermined data; perform a real capacity recovery for making each recovery target real page into an unallocated state, transmit a first notification, when the number of recoverable pages is equal to or less than the second threshold value but a summation of the number of recoverable real pages and a number of recovery candidate real pages is more than the second threshold value, wherein the move-source real page is a recoverable real page which is a real page in which the number of real regions storing the predetermined data is more than a first threshold value, and wherein the recovery candidate real pages are real pages in which the number of real regions storing invalid data not referred to by the access source is more than a third threshold value.