Large applications executing on Grid or cluster architectures consisting of hundreds or thousands of computational nodes create problems with respect to reliability. The source of the problems is node failures and the need for dynamic configuration over extensive runtime. By allowing recovery even under different numbers of processors, the approaches are especially suitable for applications with a need for adaptive or reactionary configuration control. The low-cost protocols offer the capability of controlling or bounding the overhead. The fault-tolerance mechanisms also have to be capable of dealing with the specific characteristics of a heterogeneous and dynamic environment. Any fault that can be detected with certainty can be dealt with by our mechanisms. On one side, this includes any benign fault such as a crash fault. By allowing recovery even under different numbers of processors, the approaches are especially suitable for applications with a need for adaptive or reactionary configuration control.