Dynamic Function Placement in Active Storage Clusters (CMU-CS-99-140)

Optimally partitioning application and filesystem functionality within a cluster of clients and servers is a difficult problem due to dynamic variations in application behavior, resource availability and workload mixes. This paper presents ABACUS, a run-time system that monitors and dynamically changes function placement for applications that manipulate large data sets. Several examples of data-intensive workloads are used to show the importance of proper function placement and its dependence on dynamic run-time characteristics, with performance differences frequently reaching 2-10X. We evaluate how well the ABACUS prototype adapts to run-time system behavior, including both long-term variation (e.g., filter selectivity) and short-term variation (e.g., multi-phase applications and inter-application resource contention). Our experiments with ABACUS indicate that it is possible to adapt in all of these situations and that the adaptation converges most quickly in those cases where the performance impact is most significant.