A computer cluster system includes a plurality of computer groups each having a plurality of computer nodes. For each of the computer groups, the computer nodes cooperatively form a first ring topology, and one of the computer nodes serves as a first-ring master node of the first ring topology. The first-ring master nodes of the first ring topologies cooperatively form a second ring topology, and one of the first-ring master nodes serves as a second-ring master node of the second ring topology.