a small number of nodes and stores the results, so the simulator can use them and simulate activities on a much larger number of nodes. The emulator stores information of sequential execution blocks (SEBs) for multiple processors in log files, with each SEB recording the messages sent, their sources and destinations, dependencies, timings, etc. The simulator reads the log files and simulates them, and may star additional messages which are then also stored as SEBs. The simulator can thus provide a view of the performance of very large applications, based on the execution traces provided by the emulator on a much smaller number of nodes, before the entire machine is available, or configured. See also High-availability cluster Performance simulation Supercomputing References Cluster computing Supercomputing Inter-process communication