Patent ID: 7093087

Claim:
A disk array device, comprising: a plurality of disk drives; and a disk controller being coupled to at least one information processing device and storing data sent from said at least one information processing device in a first plurality of logical volumes relating to the disk drives and controlling a first group having both the first plurality of logical volumes and a second plurality of logical volumes and relating data stored in the first plurality of logical volumes to the second plurality of logical volumes; wherein the disk controller processes to receive a command; start, in accordance with the command, changing from a first status to a second status in which a relationship between the first plurality of logical volumes and the second plurality of logical volumes is split so that the second plurality of logical volumes can be accessed from said at least one information processing device or another information processing device via the disk controller; receive a write command, sent from said at least one information processing device, and being targeted to a first logical volume of the first plurality of logical volumes during a period of changing from the first status to the second status; write data related to the write command to the first logical volume and not write the data related to the write command to a second logical volume, of the second plurality of logical volumes, relating to the first logical volume based on receiving the write command; and complete changing from the first status to the second status after writing data related to the write command to the first logical volume; and wherein consistency of data stored in the second plurality of logical volumes in the second status is maintained.