SC12 Home > SC12 Schedule > SC12 Presentation - Characterizing Output Bottlenecks in a Supercomputer

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

ROOM:355-EF

ABSTRACT:
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.

Chair/Author Details:

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

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Characterizing Output Bottlenecks in a Supercomputer

SESSION: Analysis of I/O and Storage

EVENT TYPE: , 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

ROOM:355-EF

ABSTRACT:
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.

Chair/Author Details:

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

Add to iCal  Click here to download .ics calendar file

Add to Outlook  Click here to download .vcs calendar file

Add to Google Calendarss  Click here to add event to your Google Calendar