Characterizing output bottlenecks in a supercomputer

Conference · Sun Jan 01 00:00:00 EST 2012

OSTI ID:1063838

Xie, Bing ^[1]; Chase, Jeffrey ^[1]; Dillow, David A ^[2]; Drokin, Oleg ^[3]; Klasky, Scott A ^[2]; Oral, H Sarp ^[2]; Podhorszki, Norbert ^[2]

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1. Duke University
2. ORNL
3. Intel Corporation

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.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Sciences (NCCS)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1063838
• Resource Relation: Conference: IEEE/ACM SC Conference on High Performance Computing Networking, Storage and Analysis, Salt Lake City, UT, USA, 20121111, 20121115
• Country of Publication: United States
• Language: English