The first two days of this week, I occupied part of my day listening to the presentations and discussion at the ATLAS Western Tier 2 User’s Forum at SLAC. A “Tier 2” computing facility, according to the ATLAS computing model, is one which has the resources available to maintain data on disk for physics analysis, both by individuals and groups. SLAC is a Tier 2, and this was a chance to collect feedback from users about their experience while also telling them about new developments or tools to ease their lives. Things weren’t always in the easy direction, of course.
A few things stood out to me. The first was a very good presentation delivered by a SLAC graduate student relating his own experiences as a user doing physics analysis at SLAC. He discussed topics that spanned the space from getting critical data sets, to using the GRID, to running jobs in SLAC batch. As a newcomer to this experiment, I found this talk at a level particularly engaging for my own needs. Every site is a little different, but I presume that the common set of successes and frustrations likely remains the same at any location.
The other was the sheer challenge to collecting resources at a site so that enough people can do all the things they will need to do to achieve solid physics analysis. This challenge crosses many boundaries – CPUs, disk space, tape storage, purchasing, electrical infrastructure, cooling, and politics. The discussions on this particular issue – resource procurement and management – were especially interesting. The underlying concern in everybody’s mind seems to be that no matter how much you think you need now, it might not be enough come the arrival of real data.