INFN Computing Models and Grid Organization for LHC Experiments

1. Exp’s Computing Models and INFN RCs (first reaction) • Preamble • INFN RCs and Grid organization will be driven by Experiments’ needs and approved scientific program (by INFN and by LHC Collaboration) • Computing Models must agree with a possible and reasonably funding plan of investments for: • Resources (Hw, Mw, Sw, Network) • Personnel • Tier1, Tier2s and Tier3s roles and commitments • GRID realities and implementations in Italy and other LHC Countries • INFN is committed for support to the all four LHC Experiments • Even if with slightly different participation • INFN RCs spread over the “single” Tier1 (at CNAF-Bologna) and several Tier2s and Tier3s (more than ~20 overall the 4 Exps) • INFN participation is mostly conveyed via LCG Project (beside the experiments’ specific engagements) and the support to: • CERN as the Laboratory in which INFN is a Member contributing State • The Tiers in Italy • The Grid “World” (EU, US or JP) Projects

2. Cont. (INFN RCs) • Considerations • The Exps’ Computing Models are still not defined enough • Amount of data to be stored and served at the Tier1s is at reasonable state, however the amount of data to be served by the Tier2s and Tier3s…) is far to be defined • The level of services needed to serve the data at Tier1s (and Tier0+CERN Tier1) are still to be defined to allow for plans, at least in Italy • The different and various Grid flavors are still under evaluation by the Experiments • Difficult to say if the services of so different (nowadays) implementations can “all” be served • Numbers for data access and elaboration (including the rate of data acquisition, storage and distribution) are widely spread among the Exps • Could be natural for four competing Experiments, but… • The dominating “number” of the Models, that’s to say the ANALYSIS load by the Physicist is yet to be evaluated: • ALL the current Models are based on “SIMULATIONS” of MC events, not real Analysis

3. Cont. (INFN RCs) • RCs (Tier1 and Tier2s in Italy) have the mandate (by INFN) to: • Short Term: • Serve the Data Challenges of the Experiments to better define the Computing Models • Understand the Analysis load and needs, to build the services needed for that scope: • Set the final (2008) scale of resources, services and personnel • Develop/consolidate the tools for data service and flow • Develop/consolidate the tools for “end user” analysis • Longer Term: • Plan for a progressive growth of services/resources up to the final (2008) System, and plan for following years and new Luminosity of LHC • Understand the Models and the possible Commonalities (sharing) among the Experiments for a Global affordable and efficient Computing System • All the above considerations are today intended by INFN within the LCG Project, for a coordination of available resources, given the priorities defined by the Funding Agencies