Italian Tiers Hybrid Infrastructures for Large Scale CMS Data Handling and Challenge Operations

The CMS experiment is travelling its path towards the real LHC data handling by building and testing its Computing Model through daily experience on production-quality operations as well as in challenges of increasing complexity. The capability to simultaneously adress both these complex tasks on a regional basis, e.g. within INFN, relies on the quality of the developed tools and related know-how, and on their capabilityto manage switches between testbed-like and production-like infrastructures, to profit from the configuration flexibility of a unique robust data replication system, to adapt to evolving scenarios in distributed data access and analysis. The work done in INFN in the operations of Tier-1 and Tier-2 centres within event simulation, data distribution and data analysis activities, in daily production-like activities as well within LCG Service Challenges, are here presented and discussed.