First and second storage apparatuses respectively and internally set a remote copy pair for copying data of a first volume to a second volume and associate a third volume with a remote copy pair according to an external command. When an I/O request to the first volume ends in an error, a host computer sends an I/O request directed to the second volume to the second storage apparatus. If the first and the second storage apparatuses detect a failure in the first or the second storage apparatus of the other side or a connection failure between the first and the second storage apparatuses, the first and the second storage apparatuses store in the third volume a failure information flag showing that the failure was detected.