Patent ID: 7003645

Claim:
A method for liveness determination in a cluster of data processing nodes, said method on a first data processing node comprising the step of: providing at least two paths for communication of liveness information in which at least one of said paths includes a shared nonvolatile data storage device; determining whether an area on said shared nonvolatile data storage device is available for writing; and writing data, including an undated sequence number, from a first data processing node to said area on said shared nonvolatile data storage device if it is determined that said area on said shared nonvolatile data storage device is available; whereby said first node is able to determine when said area on said shared nonvolatile data storage device is available for writing after said data and said undated sequence number is transferred to a second node having read-only access to said area on said nonvolatile data storage device; and wherein said path with said nonvolatile data storage device is employed substantially continuously and concurrently with other liveness determination paths, whereby node liveness is determinable without having to resort to using secondary communication paths that are triggered by indications of liveness failure over other communication paths.