Patent ID: 7441142

Claim:
A data transfer method for transferring data frames according to Fibre Channel Protocol between a first storage control unit and a second storage control unit in a remote copy system, wherein the remote copy system includes the first storage control unit, which is connected to an information processor and sends and receives data to and from the information processor, and the second storage control unit, which is connected via a communication tool to the first-storage control unit and receives data from the first storage control unit, and wherein a buffer-to-buffer credit value applied to the data frame transfer is increased according to the distance between the first storage control unit and the second storage control unit, the method comprising the steps of: having the first storage control unit log into the second storage control unit; sending a specified data frame from the first storage control unit to the second storage control unit; measuring the time that elapses between the time the data frame is transmitted and the time a Receiver Ready signal is received by the first storage control unit from the second storage control unit; and increasing the buffer-to-buffer credit value based on the elapsed time.