SCHEDULE: NOV 10-16, 2012
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Characterizing Output Bottlenecks in a Supercomputer
SESSION: Analysis of I/O and Storage
EVENT TYPE: Papers, Best Student Paper Finalists, Best Paper Finalists
TIME: 11:30AM - 12:00PM
SESSION CHAIR: Robert B. Ross
AUTHOR(S):Bing Xie, Jeff Chase, David Dillow, Oleg Drokin, Scott Klasky, Sarp Oral, Norbert Podhorszki
Supercomputer I/O loads are often dominated by writes. HPC (High Performance Computing) file systems are designed to absorb these bursty outputs at high bandwidth through massive parallelism. However, the delivered write bandwidth often falls well below the peak. This paper characterizes the data absorption behavior of a center-wide shared Lustre parallel file system on the Jaguar supercomputer. We use a statistical methodology to address the challenges of accurately measuring a shared machine under production load and to obtain the distribution of bandwidth across samples of compute nodes, storage targets, and time intervals. We observe and quantify limitations from competing traffic, contention on storage servers and I/O routers, concurrency limitations in the client compute node operating systems, and the impact of variance(stragglers) on coupled output such as striping. We then examine the implications of our results for application performance and the design of I/O middleware systems on shared supercomputers.
Robert B. Ross (Chair) - Argonne National Laboratory
Bing Xie - Duke University
Jeff Chase - Duke University
David Dillow - Oak Ridge National Laboratory
Oleg Drokin - Whamcloud, inc.
Scott Klasky - Oak Ridge National Laboratory
Sarp Oral - Oak Ridge National Laboratory
Norbert Podhorszki - Oak Ridge National Laboratory