TY - GEN
T1 - A job pause service under LAM/MPI+BLCR for transparent fault tolerance
AU - Wang, Chao
AU - Mueller, Frank
AU - Engelmann, Christian
AU - Scott, Stephen L.
PY - 2007
Y1 - 2007
N2 - Checkpoint/restart (C/R) has become a requirement for long-running jobs in large-scale clusters due to a meantime-to-failure (MTTF) in the order of hours. After a failure, C/R mechanisms generally require a complete restart of an MPI job from the last checkpoint. A complete restart, however, is unnecessary since all but one node are typically still alive. Furthermore, a restart may result in lengthy job requeuing even though the original job had not exceeded its time quantum. In this paper, we overcome these shortcomings. Instead of job restart, we have developed a transparent mechanism for job pause within LAM/MPI+BLCR. This mechanism allows live nodes to remain active and roll back to the last checkpoint while failed nodes are dynamically replaced by spares before resuming from the last checkpoint. Our methodology includes LAM/MPI enhancements in support of scalable group communication with fluctuating number of nodes, reuse of network connections, transparent coordinated checkpoint scheduling and a BLCR enhancement for job pause. Experiments in a cluster with the NAS Parallel Benchmark suite show that our overhead for job pause is comparable to that of a complete job restart. A minimal overhead of 5.6% is only incurred in case migration takes place while the regular checkpoint overhead remains unchanged. Yet, our approach alleviates the need to reboot the LAM run-time environment, which accounts for considerable overhead resulting in net savings of our scheme in the experiments. Our solution further provides full transparency and automation with the additional benefit of reusing existing resources. Executing continues after failures within the scheduled job, i.e., the application staging overhead is not incurred again in contrast to a restart. Our scheme offers additional potential for savings through incremental checkpointing and proactive diskless live migration, which we are currently working on.
AB - Checkpoint/restart (C/R) has become a requirement for long-running jobs in large-scale clusters due to a meantime-to-failure (MTTF) in the order of hours. After a failure, C/R mechanisms generally require a complete restart of an MPI job from the last checkpoint. A complete restart, however, is unnecessary since all but one node are typically still alive. Furthermore, a restart may result in lengthy job requeuing even though the original job had not exceeded its time quantum. In this paper, we overcome these shortcomings. Instead of job restart, we have developed a transparent mechanism for job pause within LAM/MPI+BLCR. This mechanism allows live nodes to remain active and roll back to the last checkpoint while failed nodes are dynamically replaced by spares before resuming from the last checkpoint. Our methodology includes LAM/MPI enhancements in support of scalable group communication with fluctuating number of nodes, reuse of network connections, transparent coordinated checkpoint scheduling and a BLCR enhancement for job pause. Experiments in a cluster with the NAS Parallel Benchmark suite show that our overhead for job pause is comparable to that of a complete job restart. A minimal overhead of 5.6% is only incurred in case migration takes place while the regular checkpoint overhead remains unchanged. Yet, our approach alleviates the need to reboot the LAM run-time environment, which accounts for considerable overhead resulting in net savings of our scheme in the experiments. Our solution further provides full transparency and automation with the additional benefit of reusing existing resources. Executing continues after failures within the scheduled job, i.e., the application staging overhead is not incurred again in contrast to a restart. Our scheme offers additional potential for savings through incremental checkpointing and proactive diskless live migration, which we are currently working on.
UR - http://www.scopus.com/inward/record.url?scp=34548768671&partnerID=8YFLogxK
U2 - 10.1109/IPDPS.2007.370307
DO - 10.1109/IPDPS.2007.370307
M3 - Conference contribution
AN - SCOPUS:34548768671
SN - 1424409101
SN - 9781424409105
T3 - Proceedings - 21st International Parallel and Distributed Processing Symposium, IPDPS 2007; Abstracts and CD-ROM
BT - Proceedings - 21st International Parallel and Distributed Processing Symposium, IPDPS 2007; Abstracts and CD-ROM
T2 - 21st International Parallel and Distributed Processing Symposium, IPDPS 2007
Y2 - 26 March 2007 through 30 March 2007
ER -