Exploring reliability of exascale systems through simulations

Exascale computers are predicted to emerge by the end of this decade with millions of nodes and billions of concurrent cores/threads. One of the most critical challenges for exascale computing is how to effectively and efficiently maintain the system reliability. Checkpointing is the state-of-the-art technique for high-end computing system reliability that has proved to work well for current petascale scales. This paper investigates the suitability of checkpointing mechanism for exascale computers, across both parallel filesystems and distributed filesystems. We built a model to emulate exascale systems, and developed a simulator, RXSim, to study its reliability and efficiency. Experiments show that the overall system efficiency and availability would go towards zero as system scales approach exascale with checkpointing mechanism on parallel filesystems. However, the simulations suggest that a distributed filesystem with local persistent storage would offer excellent scalability and aggregate bandwidth, enabling efficient checkpointing at exascale.