Information system, including: first and second storage apparatuses connected to a host computer and including volumes designated by a common volume identifier, but being accessible via differing paths of differing priorities. A failure detection storage apparatus connected to the storage apparatuses includes a third volume. Any I/O request designating the common volume identifier, is first sent to the first volume though the first access path, but upon error is then sent to the second volume thorough the second access path. The first or second storage apparatus detecting failure stores, in the third volume, a failure information flag. Upon receiving an I/O request through the second access path, the second storage apparatus determines whether the failure information flag is stored in the third volume, and sends an error reply of the I/O request to the host computer if the failure information flag is stored in the third volume.