Process Allocation in Fault - Tolerant

Process allocation is important for fault-tolerant multi-computer systems since it directly aaects the performance and dependability of the system. In this paper, we consider load-balancing process allocation for fault-tolerant systems that balances the load before as well as after faults start to degrade the performance of the system. We show two schemes to tolerate multiple faults in the passive replica process model. The rst scheme is running multiple backup processes for each process. The second scheme is running only one backup process for each process, but regenerates backup processes for processes that do not have a backup process after a fault occurrence to keep the primary-backup process pair available. In both schemes, we propose heuristic process allocation methods for balancing loads in spite of the occurrence of faults. Simulation is used to compare the performance of both schemes. In each scheme, we are able to keep the load balanced reasonably among nodes after each fault occurrence. But, the single backup scheme is more suitable for tolerating multiple faults than the multiple backup scheme since the former has less overhead and better performance.