| 摘要 |
PROBLEM TO BE SOLVED: To selectively back up difference of any of the logic volumes allocated to a plurality of operating systems in a virtualized environment where the plurality of operating systems are executed.SOLUTION: A storage device includes: a plurality of virtual volumes; a master volume for storing data according to I/O access to the plurality of virtual volumes; a difference volume for storing difference data for the data stored in the master volume; and a volume management map including a flag to be copied for each of the plurality of virtual volumes. In response to the I/O access from a host computer, a determination is made as to whether the volume of the difference data in the accumulated area of the difference volume exceeds a predetermined threshold value. If it is determined to exceed the predetermined threshold value, the difference data stored in the accumulated area of the difference volume is moved to a transfer area. The difference data stored in the transfer area is backed up into an external storage device. |
