Load balancing schemes for high-throughput distributed fault-tolerant servers

Clusters of workstations, connected by a fast network, are emerging as a viable architecture for building high-throughput fault-tolerant servers. This type of architecture is more scalable and more cost-effective than a tightly coupled multiprocessor and may achieve as good a throughput. We explore several combinations of fault tolerance (FT) and load-balancing (LB) schemes, and compare their impact on the maximum throughput achievable by the system, and on its survivability. In particular, we show that the FT scheme has an effect on the throughput of the system, while the LB scheme affects the ability of the system to override failures. We study the scalability of the different schemes under different loads and failure conditions. Our simulations take into consideration the overhead of each scheme, the network contention, and the resource loads.