5th EGEE User Forum

CMS Remote Analysis Builder (CRAB) with the ARC grid middleware

14 Apr 2010, 14:20

20m

Room X (Uppsala University)

Oral Software services exploiting and/or extending grid middleware (gLite, ARC, UNICORE etc) High Energy Physics

Speaker

Mr Erik Edelmann (CSC - Finnish IT Centre for Science)

Description

The Compact Muon Solenoid (CMS) is one of the general purpose experiments at the CERN Large Hadron Collider (LHC). For distributing analysis jobs to computational resources scattered across the world, the CMS project has developed the CMS Remote Analysis Builder software (CRAB). Until now CRAB has only supported the gLite and OSG middlewares, but with the help of a new plugin, the CMS analysis jobs can be run on sites running the ARC middleware.

Conclusions and Future Work

CRAB can used in a standalone mode or through a server managing the users
job on the grid. In standalone mode the CRAB ARC plugin has been proven to
handle the CRAB analysis jobs succesfully. This method has the drawback of
only being able to use one middleware type at the time. The CRAB ARC plugin will be
integrated with the CRAB server to enable transparent job submission to all
middleware flavors in use in CMS. This will removes the last large obstacle
of completely transparent usage across middlewares.

Impact

The sites supporting the CMS experiment have predominantly run only on
gLite and OSG middlewares. When the CMS tools better support different
middlewares, the sites have more freedom choosing how to run their site. By
making the CMS tools more middleware agnostic this also helps the users use
the largest amount of resources, transparently and efficiently.

Detailed analysis

CRAB uses the underlying grid middleware to find a computing
element (CE) close to an storage element (SE) where the data to be
analyzed resides, and submit the jobs there. CRAB uses the
middleware with the help of plugins. These plugins have been available
for the gLite and OSG middlewares. The Tier-2 center hosted by Helsinki
Institute of Physics (HIP) uses the ARC grid middleware. To enable CRAB
jobs on HIP, two methods are being used. The first is based on grid
level interoperability between ARC and gLite grid middlewares, together
with the gLite plugin for CRAB. Recently, also an ARC plugin for CRAB
has been developed, to enable jobsubmission using an ARC UI and native
interaction between CRAB and ARC. This plugin allows CRAB to better
support ARC, and enables CRAB to use all its features for jobhandling.

Presentation materials

Slides

cms_on_arc.pdf