A Lightweight Data Location Service for Nondeterministic Exascale Storage Systems

In this article, we present LWDLS, a lightweight data location service designed for Exascale storage systems (storage systems with order of 1018 bytes) and geo-distributed storage systems (large storage systems with physically distributed locations). LWDLS provides a search-based data location solution, and enables free data placement, movement, and replication. In LWDLS, probe and prune protocols are introduced that reduce topology mismatch, and a heuristic flooding search algorithm (HFS) is presented that achieves higher search efficiency than pure flooding search while having comparable search speed and coverage to the pure flooding search. LWDLS is lightweight and scalable in terms of incorporating low overhead, high search efficiency, no global state, and avoiding periodic messages. LWDLS is fully distributed and can be used in nondeterministic storage systems and in deterministic storage systems to deal with cases where search is needed. Extensive simulations modeling large-scale High Performance Computing (HPC) storage environments provide representative performance outcomes. Performance is evaluated by metrics including search scope, search efficiency, and average neighbor distance. Results show that LWDLS is able to locate data efficiently with low cost of state maintenance in arbitrary network environments. Through these simulations, we demonstrate the effectiveness of protocols and search algorithm of LWDLS.