Dr Tony Wildish (PRINCETON)
PhEDEx, the CMS data- placement system, uses the FTS service to transfer files. Towards the end of 2007 PhEDEx was beginning to show some serious scaling issues, with excessive numbers of processes on the site VOBOX running PhEDEx, poor efficiency in use of FTS job-slots, high latency for failure-retries, and other problems. The core PhEDEx architecture was changed in May 2008 to eliminate these problems. By introducing cooperative multi-threading we could adopt a more modular approach, resulting in fewer FTS job-submissions, constant file-level monitoring load on the FTS server regardless of throughput, link-level optimisation, fewer processes on the VOBOX, and fewer connections to the central Oracle database.