Patent ID: 7277952

Claim:
In a distributed computer system having nodes capable of accessing a resource, a method comprising: at a first node, executing a first arbitration process and taking ownership of the resource including placing a persistent reservation on the resource that prevents other nodes from accessing the resource and from clearing the persistent reservation through a bus reset; at a second node, executing a second arbitration process and challenging the persistent reservation by: 1) modifying the persistent reservation at the first node into a modified persistent reservation that prevents other nodes from accessing the resource, the modifying of the persistent reservation performed such that the resource cannot be accessed during the transition to the modified persistent reservation; and 2) enabling the first node to defend its persistent reservation; and at the second node, determining whether the first node failed to defend its persistent reservation, and if not defended, taking; ownership of the resource such that the second node places a persistent reservation on the resource that prevents other nodes from accessing the resource.