Abstract: Apparatus and methods for detecting failure of a node in a cluster computer system. The apparatus include controllers programmed to cooperate. In one embodiment, the apparatus include first and second nodes with respective bus controllers communicatively coupled to each other and to a logical I/O device by means of a bus. The first node firstly recognizes the the second node as a node in the cluster. At some later point, a node whose communicative coupling has failed node is coupled to the cluster a second time. The first node recognizes this second coupling and, in response, queries the second node for failure-status information. The first and second nodes negotiate membership in the cluster for the second node on the first node's determining that the second node was the node that failed between the first and second couplings. Various embodiments follow: The first node firstly recognizes the second node as either a master or a slave node in the cluster.

Abstract: Methods for re-configuring a cluster computer system of multiple or more nodes when the cluster experiences communications failure. First and second nodes of the cluster have respective channel controllers. A SCSI channel and the controllers communicatively connect the multiple nodes. When a node becomes aware of a possible communications failure, the node attempts to determine the authenticity the failure and responds according to the determined authenticity. According to one method, a first node detects heartbeat node-to-node communications failure on the channel and then tests a physical drive on the channel. If the testing is successful, the node kills the other node. If the testing is unsuccessful, the first node commits suicide. In one embodiment, the coupling includes multiple channels communicatively coupling the first and second nodes and the first node selecting one of the channels for node-to-node communications.