21-25 May 2012
New York City, NY, USA
US/Eastern timezone

A gLite FTS based solution for managing user output in CMS

22 May 2012, 13:30
4h 45m
Rosenthal Pavilion (10th floor) (Kimmel Center)

Rosenthal Pavilion (10th floor)

Kimmel Center

Poster Distributed Processing and Analysis on Grids and Clouds (track 3) Poster Session

Speakers

Daniele Spiga (CERN) Hassen Riahi (Universita e INFN (IT)) Mattia Cinquilli (Univ. of California San Diego (US))

Description

The CMS distributed data analysis workflow assumes that jobs run in a different location to where their results are finally stored. Typically the user output must be transferred across the network from one site to another, possibly on a different continent or over links not necessarily validated for high bandwidth/high reliability transfer. This step is named stage-out and in CMS was originally implemented as a synchronous step of the job execution. However, our experience showed the weakness of this approach both in terms of low total job execution efficiency and failure rates, wasting precious CPU resources. The nature of analysis data makes it inappropriate to use PhEDEx, CMS' core data placement system. As part of the new generation of CMS Workload Management tools, the Asynchronous Stage-Out system (AsyncStageOut) has been developed to enable third party copy of the user output. The AsyncStageOut component manages glite FTS transfers of data from a temporary store at the site where the job ran to the final location of the data on behalf of that data owner. The tool uses python daemons, built using the WMCore framework, talking to CouchDB, to manage the queue of work and FTS transfers. CouchDB also provides the platform for a dedicated operations monitoring system. In this paper, we present the motivations of the asynchronous stage-out system. We give an insight into the design and the implementation of key features, describing how it is coupled with the CMS workload management system. Finally, we show the results and the commissioning experience.

Primary author

Co-authors

Dr Eric Wayne Vaandering (Fermi National Accelerator Lab. (US)) Hassen Riahi (Universita e INFN (IT)) Marco Mascheroni (Nat. Inst. of Chem.Phys. & Biophys. (EE)) Mattia Cinquilli (Univ. of California San Diego (US))

Presentation Materials