Storage switch, storage system, and data copying method using bitmaps representing different sized regions

Abstract

A storage switch includes a first bitmap generator for generating a first bitmap, a controller for controlling copying of data, a first modifier, a second bitmap generator for generating a second bitmap, a second modifier, a merging controller for controlling to generate a third bitmap. When the writing of data is performed during the copying of data, the merging controller modifies a part of the index bits in the third bitmap corresponding to a part of the index bits of the first bitmap modified by the first modifier on account of the copying of data performed before the writing of data, and merges the second bitmap modified by the second modifier and the third bitmap modified by the merging controller. The controller resumes copying of data of any sub-regions on the basis of the merged bitmap.