Patent ID: 7979663

Claim:
A storage apparatus which configures an array that combines one or more storage media and defines storage areas of the storage media as a continuous single area, segments an entire area of the array into a plurality of physical extents, and configures and allocates a logical disk recognizable from a host computer by combining one or more physical extents, the apparatus comprising: a unit configured to manage correspondences of the physical extents to the logical disk accessed from the host computer, and to reserve a physical extent corresponding to a logical extent of interest among logical extents, on the logical disk, associated with the physical extents every time a write access is received from the host computer; a unit configured to generate a predetermined data pattern and to return the predetermined data pattern as read data in response to a read request from the host computer; a deleting unit configured to detect whether or not an entire area of the reserved physical extent defines the predetermined data pattern by checking a data pattern of a storage area every time an access to the storage media is made or periodically, and to delete, when the entire area of the reserved physical extent defines the predetermined data pattern, a logical disk allocation of the reserved physical extent; and a unit configured to detect, when the host computer issues a delete request of data of a file created on the logical disk, that the entire area of the reserved physical extent defines the predetermined data pattern by writing the predetermined data pattern in a storage area where the data to be deleted was stored, to release the reserved physical extent, and to return the predetermined data pattern when the host computer issues a read request to the logical extent corresponding to the released physical extent, wherein the deleting unit checks the data pattern of the storage area in turn from a first sector of the physical extent, holds an unused end address as an address of a last sector of the continuous predetermined data pattern, sets an address of a sector immediately before checked sectors which undergo a write access as the unused end address when the write access is made to the checked sectors, determines that the entire area of the physical extent is unused when the unused end address matches an end address of the physical extent, and deletes the logical disk allocation of the physical extent.