Patent ID: 7284103

Claim:
A data copy method for a disk sub system that is equipped with a first storage apparatus including a first logic storage apparatus divided into a first region and a second region and a second storage apparatus including a second logic storage apparatus divided into a first region and a second region, the first logic storage apparatus and the second logic storage apparatus connecting to a host apparatus, wherein data on the first logic storage apparatus is copied to the second logic storage apparatus by an instruction from the host apparatus, the data copy method comprising the steps of: designating the second logic storage apparatus as a copy destination for copying data of the first logic storage apparatus based on a first command to designate a copy source and a copy destination; switching the second region of the first logic storage apparatus and the second region of the second logic storage apparatus with one another; such that the first logic storage apparatus comprises the first region of the first storage apparatus and second region of the second storage apparatus, and the second logic storage apparatus comprises the first region of the second storage apparatus and the second region of the first storage apparatus; and copying data stored in the first storage apparatus to the second storage apparatus based on a second command to designate to create a copy of data; receiving a third command from the host apparatus for releasing the designation of the copy source and the copy destination; making a determination of: (1) if a position where switching between the second region of the first logic storage apparatus and the second region of the second logic storage apparatus is completed is located after a position where copying is completed, and (2) if the position where copying is completed is not in the first region; switching data of the first logic storage apparatus and data of the second logic storage apparatus with one another when the determinations of (1) and (2) are both positive.