Patent ID: 6907543

Claim:
A clustering system comprising: a first cluster including a first host device and a first storage device coupled to the first host device; a second cluster including a second host device and a second storage device coupled to the second host device; a heartbeat network coupled to each of the first and second host devices; a remote copy interface coupling the first and second storage devices; clustering software to control fail over between the first and second host devices is configured in each of the first and second host devices; paired volume control software to issue a pair control command configured in the first and second host devices; and a determining volume is provided in each of the first and second storage devices; wherein the clustering software, when it detects a failure by monitoring the heartbeat, issues a selected command to the paired volume control software requiring an exclusive process between paired volumes; wherein the paired volume control software issues the pair control command to the determining volume when receiving the selected command from the clustering software; wherein the paired volume control software receiving a normal end status returns normal end status to the clustering software; and wherein the clustering software receiving the normal end status from the pair volume control software starts a fail over process.