Speaker
Robert Snihur
(University of Nebraska (US))
Description
There are approximately 60 Tier-3 computing sites located on campuses of collaborating institutions in CMS. We describe the function and architecture of these sites, and illustrate the range of hardware and software options. A primary purpose is to provide a platform for local users to analyze LHC data, but they are also used opportunistically for data production. While Tier-3 sites vary widely in size (number of nodes, users, support personnel), there are some common features. A site typically has a few nodes reserved for interactive use and to provide services such as an interface to the GRID. The remainder of the nodes are usually available for running CPU intensive batch jobs; a future plan will allow jobs to flock to other clusters on campus. In addition, data storage systems may be provided and we discuss several models in use, including the new paradigm of a diskless site with wide area access to data via a global XROOTD redirector. Compared to Tier-1 and Tier-2 sites, the Tier-3 sites are highly flexible and are designed for easy operation. Their ultimate configuration balances cost, performance, and reliability.
Primary author
Robert Snihur
(University of Nebraska (US))
