Patent ID: 7596660

Claim:
A method for load distribution among a plurality of data controllers that receive a data input/output request from an external communication path and perform data input/output processing with respect to a storage resource in response to the data input/output request, the plurality of data controllers being connected by a data communication path and being able to communicate with each another, the method comprising: receiving, at a first data controller from among the plurality of data controllers, the data input/output request; performing, at the first data controller, input/output operations with the storage resource on data associated with the data input/output request; and performing, at a second data controller from among the plurality of data controllers, parity calculations for the data associated with the data input/output request, the first data controlled further determining whether or not it is designated to perform the parity calculation, wherein if the first data controller is designated to perform the parity calculation, then the first data controller and the second data controller are the same data controller, wherein if the first data controller is not designated to perform the parity calculation, then the first data controller is different from the second data controller.