Patent ID: 7051121

Claim:
A method for controlling a storage system including a host computer, and a first and a second storage control apparatuses each having a function for receiving a data input/output request transmitted from said host computer and executing a data input/output process for a storage device in response to said data input/output request received, comprising: connecting a first communication path between said host computer and said first storage control apparatus; connecting a second communication path between said first storage control apparatus and said second storage control apparatus; receiving by said first storage control apparatus a first data input/output request transmitted from said host computer through said first communication path; when said first storage control apparatus has judged that said first data input/output request is not to be handled by said first storage control apparatus, transmitting by said first storage control apparatus a second data input/output request corresponding to said first data input/output request, to said second storage control apparatus through said second communication path; receiving, by said second storage control apparatus, said second data input/output request and executing a data input/output process corresponding to said second data input/output request received; said first and said second storage control apparatuses each organizing one or more logic volume(s) on a storage area provided by a storage device for which said first and said second storage control apparatuses execute respective data input/output processes; when said first storage control apparatus has received from said host computer a data write-in request of new data to said first logic volume for which said first storage control apparatus executes data input/output processes, transmitting by said first storage control apparatus said data write-in request of the new data to said second storage control apparatus without writing the new data to said first logic volume; receiving, by said second storage control apparatus, said data write-in request and writing the new data to said second logic volume for which said second storage control apparatus executes data input/output processes; transmitting by said second storage control apparatus to said first storage control apparatus the storage position of the new data in said second logic volume; and storing in said first storage control apparatus the storage position in said first logic volume which is the write-in destination of the new data, and the storage position in said second logic volume of the new data transmitted, correlating the two storage positions with each other.