Patent ID: 7610414

Claim:
A data transfer method for transferring, through use of a plurality of paths, data between a plurality of logic devices provided in an external storage device and an input/output request device which issues input/output requests to each of said plurality of logic devices of said external storage device, the method comprising: setting priority levels of said plurality of logic devices; setting a distribution proportion at which the input/output requests to each said logic device are distributed to said plurality of paths on the basis of said priority levels such that each of said plurality of logic devices other than one of said plurality of logic devices with a lowest priority defined in terms of said priority levels uses two or more of said plurality of paths, and such that the logic device with the lowest priority uses only one of said plurality of paths which is different from two or more paths used by one of said plurality of logic devices with highest priority defined in terms of said priority levels to transfer the request to the logic device with the lowest priority; and transferring said data through use of respective paths according to the distribution proportions, wherein the distribution proportions are set such that total processing volumes of respective paths assigned to a logic device becomes larger as a priority level for the logic device becomes higher.