Server decision method and device thereof

Each node of the cluster system is classified into the main server candidate node group capable of operating the specific task, the sub-server candidate node group capable of operating the specific task and the back up task thereof and the out of candidate node grope which is excluded from the operation of the specific task and the back up operation thereof. Each of the servers belonging to the main candidate node group presents its public relations information necessary for the election judgment of the main server to all the node and runs as a candidate at a boot time and, at the same time, compares its public relations information to the public relations information of other nodes and, when it determines that it is not an adequate candidate, stops the presentation of its public relations information and withdraws its candidacy and allows the only main server approved by other nodes to exist. Each of the servers belonging to the sub-server candidate node group similarly allows the only sub-server approved by other nodes to exist.