Storage system for controlling assignment of storage area to virtual volume storing specific pattern data

Abstract

A storage system comprises a storage medium including a plurality of physical storage areas. The storage system controls a host computer to recognize a logical volume having a plurality of virtual storage areas, reads the data from the physical storage area assigned to the virtual storage area of the logical volume, determines whether or not the read data includes only the specific pattern data, and cancels the assignment of the physical storage area to the virtual storage area if the read data includes only the specific pattern data.

What is claimed is: 
     
         1 . A storage system for storing the data written by a host computer, the storage system comprising a storage medium including a plurality of physical storage areas, and a controller for controlling the write of the data into the storage medium and the read of the data from the storage medium, wherein
 the controller controls the host computer to recognize a first logical volume;   a storage area space of the first logical volume includes a plurality of address ranges; and   the controller holds information for managing the assignment of the each physical storage area to the each address range;   determines whether or not the physical storage area is assigned to the address range specified by a received data write request, if the data write request for any of the address ranges of the first logical volume is received; assigns the physical storage area not yet assigned to any of the address ranges to the specified address range if the physical storage area is not assigned to the specified address range;   writes the write requested data on the data write request into the physical storage area assigned to the specified address range;   reads the data from the physical storage area assigned to the address range of the first logical volume if a predetermined condition is satisfied;   determines whether or not the read data includes the data of a predetermined pattern only;   cancels the assignment of the physical storage area to the address range if the read data includes the data of the predetermined pattern only;   determines whether or not the physical storage area is assigned to the address range specified by a data read request if the data read request for any of the address ranges of the first logical volume is received;   sends the read data to a sender of the data read request by reading the data from the physical storage area assigned to the specified address range if the physical storage area is assigned to the specified address range; and   sends the data of the predetermined pattern to the sender of the data read request if the physical storage area is not assigned to the specified address range.