Activities and performance optimization of the Italian computing centers supporting the ATLAS experiment

With this work we present the activity and performance optimization of the Italian computing centers supporting the ATLAS experiment forming the so-called Italian Cloud. We describe the activities of the ATLAS Italian Tier-2s Federation inside the ATLAS computing model and present some Italian original contributions. We describe StoRM, a new Storage Resource Manager developed by INFN, as a replacement of Castor at CNAF - the Italian Tier-1 - and under test at the Tier-2 centers. We also show the failover solution for the ATLAS LFC, based on Oracle DataGuard, load-balancing DNS and LFC daemon reconfiguration, realized between CNAF and the Tier-2 in Roma. Finally we describe the sharing of resources between Analysis and Production, recently implemented in the ATLAS Italian Cloud with the Job Priority mechanism.