Patent ID: 7975123

Claim:
A storage system comprising: a controller providing a logical unit which is used by a host computer; and physical storage devices, wherein the controller manages a first increment amount to a first continuous area in the logical unit, and a second increment amount to a second continuous area in the logical unit, wherein the controller allocates an unallocated area in the logical unit to a certain amount of storage area in the physical storage devices, in response to an input/output request from the host computer, wherein if an address of the input/output request is in the first continuous area, the certain amount is the first increment amount, wherein if an address of the input/output request is in the second continuous area, the certain amount is the second increment amount, wherein the controller updates the first increment amount or the second increment amount, in response to receiving an allocation amount from a management computer, wherein the first increment amount is smaller than a size of the first continuous area, wherein the second increment amount is smaller than a size of the second continuous area, and wherein if an address of the input/output request is a discontinuous area, which is not the first continuous area or the second continuous area, the certain amount is another value.