M. Jones (Manchester University)
The BaBar experiment has accumulated many terabytes of data on particle physics reactions, accessed by a community of hundreds of users. Typical analysis tasks are C++ programs, individually written by the user, using shared templates and libraries. The resources have outgrown a single platform and a distributed computing model is needed. The grid provides the natural toolset. However, in contrast to the LHC experiments, BaBar has an existing user community with an existing non-Grid usage pattern, and providing users with an acceptable evolution presents a challenge. The 'Alibaba' system, developed as part of the UK GridPP project, provides the user with a familiar command line environment. It draws on the existing global file systems employed and understood by the current user base. The main difference is that they submit jobs with a 'gsub' command that looks and feels like the familiar'qsub'. However it enables them to submit jobs to computer systems at different institutions, with minimal requirements on the remote sites. Web based job monitoring is also provided. The problems and features (the input and output sandboxes, authentication, data location) and their solutions are described.