Abstract: A third vote consensus technique enables a first node, i.e., a surviving node, of a two-node cluster to establish a quorum and continue to operate in response to failure of a second node of the cluster. Each node maintains configuration information organized as a cluster database (CDB) which may be changed according to a consensus-based protocol. Changes to the CDB are logged on a third copy file system (TCFS) stored on a local copy of TCFS (L-TCFS). A shared copy of the TCFS (i.e., S-TCFS) may be stored on shared storage devices of one or more storage arrays coupled to the nodes. The local copy of the TCFS (i.e., L-TCFS) represents a quorum vote for each node of the cluster, while the S-TCFS represents an additional “tie-breaker” vote of a consensus-based protocol. The additional vote may be obtained from the shared storage devices by the surviving node as a third vote to establish the quorum and enable the surviving node to cast two of three votes (i.e.

Abstract: A third vote consensus technique enables a first node, i.e., a surviving node, of a two-node cluster to establish a quorum and continue to operate in response to failure of a second node of the cluster. Each node maintains configuration information organized as a cluster database (CDB) which may be changed according to a consensus-based protocol. Changes to the CDB are logged on a third copy file system (TCFS) stored on a local copy of TCFS (L-TCFS). A shared copy of the TCFS (i.e., S-TCFS) may be stored on shared storage devices of one or more storage arrays coupled to the nodes. The local copy of the TCFS (i.e., L-TCFS) represents a quorum vote for each node of the cluster, while the S-TCFS represents an additional “tie-breaker” vote of a consensus-based protocol. The additional vote may be obtained from the shared storage devices by the surviving node as a third vote to establish the quorum and enable the surviving node to cast two of three votes (i.e.

Abstract: A third vote consensus technique enables a first node, i.e., a surviving node, of a two-node cluster to establish a quorum and continue to operate in response to failure of a second node of the cluster. Each node maintains configuration information organized as a cluster database (CDB) which may be changed according to a consensus-based protocol. Changes to the CDB are logged on a third copy file system (TCFS) stored on a local copy of TCFS (L-TCFS). A shared copy of the TCFS (i.e., S-TCFS) may be stored on shared storage devices of one or more storage arrays coupled to the nodes. The local copy of the TCFS (i.e., L-TCFS) represents a quorum vote for each node of the cluster, while the S-TCFS represents an additional “tie-breaker” vote of a consensus-based protocol. The additional vote may be obtained from the shared storage devices by the surviving node as a third vote to establish the quorum and enable the surviving node to cast two of three votes (i.e.

Abstract: A third vote consensus technique enables a first node, i.e., a surviving node, of a two-node cluster to establish a quorum and continue to operate in response to failure of a second node of the cluster. Each node maintains configuration information organized as a cluster database (CDB) which may be changed according to a consensus-based protocol. Changes to the CDB are logged on a third copy file system (TCFS) stored on a local copy of TCFS (L-TCFS). A shared copy of the TCFS (i.e., S-TCFS) may be stored on shared storage devices of one or more storage arrays coupled to the nodes. The local copy of the TCFS (i.e., L-TCFS) represents a quorum vote for each node of the cluster, while the S-TCFS represents an additional “tie-breaker” vote of a consensus-based protocol. The additional vote may be obtained from the shared storage devices by the surviving node as a third vote to establish the quorum and enable the surviving node to cast two of three votes (i.e.

Abstract: Systems, methods, apparatus and software can implement a flexible I/O fence mechanism framework allowing clustered computer systems to conveniently use one or more I/O fencing techniques. Various different fencing techniques can be used, and fencing mechanism can be customized.

Abstract: Systems, methods, apparatus and software can make use of coordinator resources and SCSI-3 persistent reservation commands to determine which nodes of a cluster should be ejected from the cluster, thereby preventing them from corrupting data on a shared data resource. Fencing software operating on the cluster nodes monitors the cluster for a cluster partition (split-brain) event. When such an event occurs, software on at least two of the nodes attempts to unregister other nodes from a majority of coordinator resources. The node that succeeds in gaining control of the majority of coordinator resources survives. Nodes failing to gain control of a majority of coordinator resources remove themselves from the cluster. The winning node can also proceed to unregister ejected nodes from shared data resources. These operations can be performed in parallel to decrease failover time. The software can continue to execute on all nodes to prevent additional problems should a node erroneously attempt to reenter the cluster.

Abstract: Systems, methods, apparatus and software can implement a flexible I/O fence mechanism framework allowing clustered computer systems to conveniently use one or more I/O fencing techniques. Various different fencing techniques can be used, and fencing mechanism can be customized.