Please refer to Oracle Notes :
Oracle Coherence and Split-Brain FAQ [ID 1069132.1]
Oracle Coherence, Split-Brain, and Recovery Protocols Example In Detail [ID 1069429.1]
Witness Protocol: The Coherence clustering protocol (TCMP) is a reliable transport mechanism built on UDP. In order for the protocol to be reliable, it requires an acknowledgement (ACK) for each packet delivered. If a packet fails to be acknowledged within the configured timeout period, the Coherence cluster member will log a packet timeout. When this occurs, the cluster member will consult with other members to determine who is at fault for the communication failure. If the witness members agree that the suspect member is at fault, the suspect is removed. If the witnesses unanimously disagree, the accuser is removed. This process is known as the witness protocol.
Panic Protocol: When the presence of more than one cluster (i.e. Split-Brain) is detected by a Coherence member, the panic protocol is invoked in order to resolve the conflicting clusters and consolidate into a single cluster. The protocol consists of the removal of smaller clusters until there is one cluster remaining. In the case of equal size clusters, the one with the older Senior Member will survive.
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