Replication is more efficient than you think

Abstract

This paper revisits replication coupled with checkpointing for failstop errors. Replication enables the application to survive many fail-stop errors, thereby allowing for longer checkpointing periods. Previously published works use replication with the no-restart strategy, which works as follows: (i) compute the application Mean Time To Interruption (MTTI) M as a function of the number of processor pairs and the individual processor Mean Time Between Failures (MTBF); (ii) use checkpointing period T no MTTI = √ 2MC à la Young/Daly, where C is the checkpoint duration; and (iii) never restart failed processors until the application crashes. We introduce the restart strategy where failed processors are restarted after each checkpoint. We compute the optimal checkpointing period T rs opt for this strategy, which is much larger than T no MTTI , thereby decreasing I/O pressure. We show through simulations that using T rs opt and the restart strategy, instead of T no MTTI and the usual no-restart strategy, significantly decreases the overhead induced by replication, in terms of both total execution time and energy consumption.

Soft errors detection and automatic recovery based on replication combined with different levels of checkpointing

“…The combination of checkpointing the output of tasks and replicating for application-specific detection is explored in [2] for a linear workflow context, in the presence of both fail-stop and silent faults. Finally, in a recent study, the authors of [21] explore the combination of replication with checkpointing for fail-stop errors, and compute the optimal checkpoint interval for this approach.…”