Scaling up ATLAS Database Release Technology for the LHC Long Run

To overcome scalability limitations in database access on the Grid, ATLAS introduced the Database Release technology replicating databases in files. For years Database Release technology assured scalable database access for Monte Carlo production on the Grid. Since previous CHEP, Database Release technology was used successfully in ATLAS data reprocessing on the Grid. Frozen Conditions DB snapshot guarantees reproducibility and transactional consistency isolating Grid data processing tasks from continuous conditions updates at the “live” Oracle server. Database Release technology fully satisfies the requirements of ATLAS data reprocessing and Monte Carlo production. It is fast (on-demand access to ~100 MB of data takes less than 10 s), robust (failure rate less than 10**-6 per job that makes 10K queries), and scalable (served 1B queries in one of the reprocessing campaigns). We parallelized the Database Release build workflow to avoid linear dependency of the build time on the length of LHC data-taking period. In recent data reprocessing campaigns the build time was reduced by an order of magnitude thanks to a proven master-worker architecture used in the Google MapReduce. We describe further Database Release optimizations scaling up the technology for the LHC long run.