It was mentioned in the conversation today that MPI_ERR_RANK_FAIL_STOP may not be the first error returned by an MPI call. In particular the MPI call may return an error symptomatic of a fail-stop process failure (e.g., network link failed - currently MPI_ERR_OTHER), before eventually diagnosing the event as a process failure. This 'space between' MPI_SUCCESS behavior and MPI_ERR_RANK_FAIL_STOP behavior is not currently defined, and probably should be for the application to cleanly move from set of semantics for one error class to another. The suggestion was to create a new general network error class (e.g., MPI_ERR_COMMUNICATION or MPI_ERR_NETWORK - MPI_ERR_COMM is taken) that can be returned when the operation cannot complete due to network issues (which might be later diagnosed as process failure and escalated to the MPI_ERR_RANK_FAIL_STOP semantics). You could also think about this error being used for network resource exhaustion as well (something that Tony mentioned during the last MPI Forum meeting). In which case retrying at a later time or taking some other action before trying again would be useful/expected. There are some issues with matching, and the implications on collective operations. If the network error is sticky/permanent then once the error is returned it will always be returned or escalated to fail-stop process failure (or more generally to a 'higher/more severe/more detailed' error class). A recovery proposal (similar to what we are developing for process failure) would allow the application to 'recover' the channel and continue communicating on it. The feeling was that this should be expanded into a full proposal, separate from the Run-Through Stabilization proposal. So we can continue with the RTS proposal, and bring this forward when it is ready. What to folks think about this idea? -- Josh -- Joshua Hursey Postdoctoral Research Associate Oak Ridge National Laboratory http://users.nccs.gov/~jjhursey