Data Centre for Astrophysics
Astronomy Department of the University of Geneva
ISDC Seminar

Thursday, 7 June 2007 at 14:00

Jamie Shiers & Patricia Mendez Lorenzo
CERN, IT Division

The Worldwide LHC Computing Grid - What? Why? How?

1st talk: In order to process and analyse the multi-PetaBytes of data from the LHC - the world's largest scientific machine - a worldwide grid service has been established, building on two main production infrastructures: those of the Open Science Grid (OSG) in the Americas, and the Enabling Grids for E-sciencE (EGEE) Grid in Europe and elsewhere. Over the past 3 years, the Worldwide LHC Computing Grid (WLCG) services have undergone a series of so-called 'service challenges' designed to ramp the service up to the required degree of availability and performance and to trigger medium/long term planning of the various sites and regions involved. Detailed service and availability targets have been drawn up by the WLCG collaboration and form part of the Memorandum of Understanding (MoU) that is signed by all participating sites. This talk summarises the main lessons learnt from deploying WLCG production services. In particular, we discuss how the somewhat ambitious targets laid out in the MoU are addressed and the various deployment strategies that are required. Finally, a simple analogy is drawn with the Web in terms of usability - what do we need to achieve to cross the chasm from small-scale adoption to ubiquity?

2nd talk: The computational and storage capability of the Grid are attracting several research communities. This talk discusses the general patterns observed in supporting new applications and porting them on the EGEE environment. We present the general infrastructure we have developed inside the application and support team at CERN (PSS and GD groups) to merge in a fast and feasible way all these applications inside the Grid, as for example Geant4, HARP, Garfield, UNOSAT or ITU. All these communities have different goals and requirements and the main challenge is the creation of a standard and general software infrastructure for the immersion of these communities onto the Grid. This general infrastructure does effectively "shield" the applications from the details of the Grid (the emphasis here is to run applications developed independently from the Grid middleware). On the other hand, it is stable enough to require few control and support by the members of the Grid team and also of the members of the users communities. Finally, it is flexible and general enough to match the requirements of the different productions without including major changes in the design of the tool.

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