US Patent 7996360 Coordinating updates to replicated data

Techniques for coordinating updates to replicated data are disclosed. For example, in a system comprised of a plurality of nodes, a method for maintaining consistent copies of data across the nodes comprises the following steps. A copy of an object o1 is maintained by a plurality of nodes. In response to a request r1 to update a copy of object o1, a message is sent to at least some of the plurality of nodes instructing a node receiving the message to invalidate its copy of object o1. In response to a node n1 receiving an invalidation message arising from r1 wherein n1 is processing another request r2 to update object o1, requests r1 and r2 are coordinated to prevent the requests from causing conflicting updates or invalidations.