Patent ID: 7991952
Filing Date: 2011-08-02
Classification: G06F

Abstract:
1. A storage system comprising: a plurality of disk drives; and a control device controlling the plurality of disk drives, the storage system is coupled to a host computer, wherein: the plurality of disk drives comprise a plurality of first disk drives and one second disk drive; the plurality of disk drives comprise a plurality of real storage areas, wherein the plurality of real storage areas of the plurality of first disk drives constitutes a first logical volume prior to the control device receiving a request for adding the second disk drive, each of the plurality of real storage areas comprises a plurality of management units of a predetermine size; and the control device is configured to: hold information indicating correspondences between a plurality of virtual storage areas to be provided for the host computer and the plurality of real storage areas assigned to the plurality of virtual storage areas; receive a request for writing data to a first virtual storage area to which a real storage area is not assigned, assign a first real storage area, which is not assigned to a virtual storage area, of the plurality of real storage areas of the plurality of first disk drives, to the first virtual storage area; distributedly store the data requested to be written in the plurality of management units contained in the first real storage area; change a size of the first logical volume so as to contain only the plurality of real storage areas assigned to the plurality of virtual storage areas, in response to receiving the request for adding the second disk drive; create a second logical volume comprising the plurality of real storage areas containing a part of the plurality of management units of the second disk drive, and the plurality of management units that are not contained in the first logical volume and are of the plurality of first disk drives; read the data stored in the plurality of management units of the plurality of first disk drives in response to receiving the request for adding the second disk drive, and distributedly store the read data in the plurality of management units of the plurality of first disk drives and the second disk drive to relocate the read data only for the plurality of management units contained in the first logical volume; receive a request for writing data to a second virtual storage area to which a real storage area is not assigned, after receiving the request for adding the second disk drive, and before the relocation of the data has been completed, assign a second real storage area, which is located in the second logical volume and not assigned to a virtual storage area, to the second virtual storage area; and wherein the control device is further configured to change, after having completed the relocation of the data, a size of the first logical volume so that the plurality of real storage areas which are not contained in both the first logical volume and the second logical volume are newly contained in the first logical volume.