Abstract: Each server of a cluster system is classified into a main server candidate server group capable of operating a specific task, a sub-server candidate server group capable of operating the specific task and a back up task, and an out of candidate server group which is excluded from operating the specific task and the back up task. Each server in the main candidate server group presents public relations information necessary for an election judgment of the main server to all servers and runs as a candidate at a boot time and, at the same time, compares this public relations information to that of other servers. When a server is determined to not be an adequate candidate, the server's presentation of public relations is stopped and the server's candidacy is withdrawn.

Abstract: 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.