Patent ID: 8738701

Claim:
At a first node of a cluster, the first node owning a persistent reservation on a storage device shared by nodes of the cluster, a method for the first node to defend against another node's attempt to preempt the first node's persistent reservation, the method comprising: after a network partition that prevents the first node from communicating with another node in the cluster, and prior to the first node being notified of the network partition, the first node detecting that another node comprising a challenger node in the cluster has attempted to reserve the storage device shared by nodes of the cluster, the detection comprising identifying that the challenger node has changed the challenger node's registration key in a registration data structure; and the first node changing the first node's registration key which was registered in the registration structure to a new registration key that the challenger node is unaware of, registering the new registration key in the registration data structure, and reserving the new registration key in a reservation data structure rather than removing any registration key associated with the challenger node from the registration data structure prior to being notified of the network partition.