Patent ID: 9122416
Filing Date: 2015-09-01
Classification: G06F

Abstract:
1. A storage apparatus coupled to a host computer, comprising: a plurality of storage devices; and a controller, wherein the controller is configured to: provide a storage pool from the plurality of storage devices, where the storage pool is comprised of a plurality of actual pages; provide one or more virtual volumes from the storage pool to the host computer, where each of the virtual volumes is comprised of virtual pages, each of the virtual pages is comprised of virtual tracks, and each of the virtual tracks is comprised of a head and records, each of the records being configured to store user data; when a target track of the virtual tracks in a target virtual page of the virtual pages is a target of a write access and the target virtual page has been allocated an actual page of the plurality of actual pages, determine whether or not the target track is a last track in the target virtual page; when the target track is the last track in the target virtual page, determine whether or not the records exist in the target virtual page; and when the records do not exist in the target virtual page, cancel the allocation of the actual page to the target virtual page, wherein determining whether or not the target track is the last track in the target virtual page is done after the write access from the host computer to the storage apparatus.