Patent ID: 8051321

Claim:
A cluster system including a plurality of client node devices and a plurality of server node devices, wherein: a first client node device of the plurality of client node devices transmits a service process request to a first service server node device of the plurality of server node devices and transmits failure detection information to a second server node device of the plurality of server node devices when the first client node device does not receive a service response from the first service server node device, and the second server node device transmits a survival confirmation request to the first server node device when the second server node device receives the failure detection information, determines that the first server node device has failed in both of a first case where the second server node device does not receive a survival confirmation response from the first server node device in a certain time period after transmitting the survival confirmation request and a second case where the second server node device receives further failure detection information from a second client node device of the plurality of client node devices in the certain time period after transmitting the survival confirmation request, and starts switching control of a server node device which performs a service process.