Alleviating scalability issues of checkpointing protocols

Current fault tolerance protocols are not sufficiently scalable for the exascale era. The most-widely used method, coordinated checkpointing, places enormous demands on the I/O subsystem and imposes frequent synchronizations. Uncoordinated protocols use message logging which introduces message rate limitations or undesired memory and storage requirements to hold payload and event logs. In this paper we propose a combination of several techniques, namely coordinated checkpointing, optimistic message logging, and a protocol that glues them together. This combination eliminates some of the drawbacks of each individual approach and proves to be an alternative for many types of exascale applications. We evaluate performance and scaling characteristics of this combination using simulation and a partial implementation. While not a universal solution, the combined protocol is suitable for a large range of existing and future applications that use coordinated checkpointing and enhances their scalability.