ALICE - ARC integration

AliEn or Alice Environment is the Grid middleware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The inter-operation has two aspects, one is the data management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. Therefore, we will concentrate on the second part. Solving it, was somewhat cumbersome, mainly due to the different computing models employed by AliEn and ARC. AliEN uses an Agent based pull model while ARC handles jobs through the more 'traditional' push model. The solution comes as a module implementing the functionalities necessary to achieve AliEn job submission and management to ARC enabled sites

Interoperating AliEn and ARC for a Distributed Tier1 in the Nordic Countries

To reach its large computing needs, the ALICE experiment at CERN has developed its own middleware called AliEn, centralised and relying on pilot jobs. One of its strength is the automatic installation of the required packages. The Nordic countries have offered a distributed Tier-1 centre for the CERN experiments, where the job management should be done with the NorduGrid middleware ARC. We have developed an interoperation module to allow to unify several computing sites using ARC, and make them look like a single site from the point of view of AliEn. A prototype has been completed and tested out of production. This talk will present implementation details of the system and its performance in tests