Patent ID: 7130941

Claim:
A method for providing data migration in a computer system, the computer system including one or more host computers, an old disk apparatus connected to said host computers via a first access path and a second access path before data migration, and a new disk apparatus newly connected to said host computers via a switch, comprising the steps of: changing-over and connecting the first access path of said old disk apparatus to said host computers via said switch connected to said new disk apparatus, wherein said host computers continue to access the old disk apparatus using the second access path; changing-over and connecting the second access path of said old disk apparatus to said host computers via said switch connected to said new disk apparatus; executing data migration from said old disk apparatus to said new disk apparatus via said switch; identifying a command for determining disk identification as an interface command from said host computers and a command for inputting and outputting data; and sending said command for determining said disk identification to said old disk apparatus.