The CREAM-CE: First experiences, results and requirements of the four LHC experiments

In terms of the gLite middleware, the current LCG-CE used by the four LHC experiments is about to be deprecated. The new CREAM-CE service (Computing Resource Execution And Management) has been approved to replace the previous service. CREAM-CE is a lightweight service created to handle job management operations at the CE level. It is able to accept requests both via the gLite WMS service and also via direct submission for transmission to the local batch system. This flexible duality provides the experiments with a large level of freedom to adapt the service to their own computing models, but at the same time it requires a careful follow up of the requirements and tests of the experiments to ensure that their needs are fulfilled before real data taking. In this paper we present the current testing results of the four LHC experiments concerning this new service. The operations procedures, which have been elaborated together with the experiment support teams will be discussed. Finally, the experiments requirements and the expectations for both the sites and the service itself are exposed in detail.