Patent ID: 7853769

Claim:
A storage system coupled to a host computer through a network, comprising: a plurality of physical storage areas for storing data written by the host computer; and a controller for controlling writing and reading of data to and from the physical storage area, wherein the plurality of physical storage areas include at least a first physical storage area and a second physical storage area, wherein the controller compares a number of remaining rewritable times for the first physical storage area and a number of remaining rewritable times for the second physical storage area and determines whether the data stored in the first physical storage area is the same as the data stored in the second physical storage area; and wherein when it is judged that the number of remaining rewritable times for the first physical storage area is less than the number of remaining rewritable times for the second physical storage area and when it is determined that the data stored in the first physical storage area is the same as the data stored in the second physical storage area, the controller writes the data written by the host computer to the second physical storage area and copies the data written in the second physical storage area to the first physical storage area.