Clustered client failover

An application instance identifier is employed with various systems and methods in order to provide a requestor with continuous access to a resource when operating in a client clustered environment. A requestor residing on a first client in may attempt to access a resource. The first client sends a request to access the resource. The request may be associated with an application instance identifier that identifiers the requestor. At some point, the first client fails and the requestor is associated with a second client via a failover mechanism. The second client sends a second request to access the resource on behalf of the requestor. The second request is associated with the requestor's application instance identifier. The application instance identifier is used to identify the second request as belonging to the same requestor as the first request, thereby granting the second request to access the resource while avoiding a conflict situation.