Patent ID: 8595549

Claim:
An information system, comprising: a first storage apparatus connected to a host computer and including a first volume designated by a volume identifier; a second storage apparatus connected to the host computer the including a second volume designated by the same said volume identifier as for the first volume; and a failure detection storage apparatus connected to the first storage apparatus and the second storage apparatus, and including a third volume; wherein, for back up purposes, the first volume and the second volume form a remote copy pair, where write data to the first volume is copied to the second volume, and the third volume is associated with the remote copy pair; wherein, for I/O request purposes, the first volume and the second volume are recognized in the information system as a single volume labeled with the same said volume identifier, but accessible by alternative access paths designated with differing priorities; wherein, a priority of a first access path from the host computer to the first volume is higher than a priority of a second access path from the host computer to the second volume; wherein, when the host computer sends an I/O request designating the same said volume identifier, the I/O request is first sent to the first volume though the first access path; wherein, when the I/O request sent to the first volume through the first access path ends in an error, the I/O request is then sent to the second volume thorough the second access path; wherein, upon receiving a write request sent to from the host computer to the second volume through the second access path, the second storage apparatus suspends the remote copy, processes the write request and stores a write location of data recorded in the second volume based on the write request; wherein, if one of the first and second storage apparatus detects a failure in the other or a connection failure between the first and second storage apparatuses, the first or the second storage apparatus detecting the failure stores, in the third volume, a failure information flag showing that the failure was detected; wherein, upon receiving the 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.