Integrating the IEKP Linux cluster as a Tier-2/3 prototype centre into the LHC Computing Grid

The local Linux cluster at the “Institut f ¨ ur Experimentelle Kernphysik” (IEKP), University of Karlsruhe, is shared between working groups of the high energy physics experiments AMS, CDF, and CMS and has successfully been integrated into the SAM grid of CDF and the LHC computing grid, LCG, for CMS while it still supports local users. This shared usage of the cluster causes heterogeneous software environments, grid middleware and access policies. Within the LCG, the IEKP site realises the concept of a Tier-2/3 prototype centre. The installation procedure and setup of the LCG middleware has been modified according to the local conditions and is described in detail in this note. With its dedicated configuration, the IEKP site offers the full grid functionality such as data transfers, CMS software installation, and grid based physics analyses. The need for prioritisation of certain user groups has been satisfied by supporting different Virtual Organisations.