Apparatus and method for maintaining consistency of shared data resources in a cluster environment

An apparatus for providing a recent set of replicas for a cluster data resource within a cluster having a plurality of nodes each having a group services client with membership and voting services to the cluster, the method comprising the steps of:

• means for broadcasting to said plurality of nodes a data resource open request having a data resource identifier and a timestamp;
• means for determining a recent replica of said cluster data resource among said plurality of nodes with respect to said timestamp of said broadcast data resource open request relative to a local timestamp of a node of the plurality of nodes associated with the data resource identifier;
• and
• means for distributing the recent replica of the cluster data resource to each node of the plurality of nodes.

An apparatus for providing a recent set of replicas for a cluster data resource, the apparatus comprising:

• a cluster having a plurality of nodes in a peer relationship, each node of said plurality of nodes having an electronic memory for storing a local replica of the cluster data resource,
• a group services client executable by each node of said plurality of nodes, said group services client having a cluster broadcasting and a cluster voting capability;
• and
• a database conflict resolution protocol (“DCRP”) executable by each node of said plurality of nodes, said DCRP interacting with said group services clients such that said DCRP broadcasts to said plurality of nodes a data resource open request having a data resource identifier and a timestamp, determines a recent replica of said cluster data resource among said plurality of nodes with respect to said timestamp of said broadcast data resource open request relative to a local timestamp of a node of said plurality of nodes associated with said data resource identifier, and distributes said recent replica of said cluster data resource to each node of said plurality of nodes.

A method for establishing a consistent set of replicas of a database within a computer cluster using cluster membership and cluster voting services, comprising the steps of:

• broadcasting an open request to other nodes to locate their corresponding replicas;
• voting to select a most recently modified replica of the database;
• determining through the voting of a source of the selected replica to be used by all participating nodes;
• and
• broadcasting the selected replica to participating nodes with differing or non-existent replicas;
• wherein a most recently modified replica is determined using a timestamp;
• wherein a checksum or cyclic redundancy value is used to further ensure consistency using the checksum or cyclic redundancy value as a low-order portion of the timestamp, and updating the checksum or cyclic redundancy value on each update of the database.