Bringing LHC data to US Tier-3s

Computer racks at the Fermilab Grid Computer Center. Image courtesy of Fermilab.

It’s a challenge for smaller research groups to get set up on a grid, but that’s exactly what physicists at over 40 sites across the United States need to do to get access to data from the Large Hadron Collider.

The new US Tier-3 centers – evenly split between the ATLAS and the Compact Muon Solenoid experiments – have each received about $30,000 in funding as part of the American Recovery and Reinvestment Act. Physicists scattered around the country will be able to use them to do their own analysis of data generated by two of the LHC experiments.

To get these sites online, a great deal of expertise will be needed. And that’s where the US LHC Tier-3 support group comes into the picture.

“What we are trying to do is to help them get their systems set up and connected to the grid, to make it easier for them to get access to data and additional processing power,” said Dan Fraser, production coordinator for the Open Science Grid.

Normally, when a new cluster gets set up on Open Science Grid, it is managed by an experienced system administrator using computers that already have networked systems, with batch schedulers running on them. The documentation, workshops, and other support offered by OSG reflect that fact. These new Tier-3 centers, on the other hand, are starting from scratch. They are generally too small to warrant the cost of an experienced system administrator. Instead, students or physicists dedicate a limited portion of their time to getting the facility up and running and then maintaining it.

LHC Computing Grid Globe in the computer center. Image courtesy of CERN.

To make the job easier, OSG is providing Tier-3 centers with onsite support during the setup of their new systems. Fraser’s team also revised the OSG documentation, adding new sections on how to create a cluster, and expanding existing sections to include more detailed instruction specifically for the Tier-3s. Likewise, OSG’s workshops have undergone some changes.

“We’ve done a lot of work on refactoring our workshops into a hands-on format so that anyone who wants to come and learn can get up and running very quickly,” Fraser said. As a result, the OSG Software Stack has evolved as well.

“We have already packaged all of the key components that you need for building a grid,” Fraser said. In the process, they have also incorporated new software to help the Tier-3s manage the large datasets they will be analyzing.

“The hope is that these changes will help not just the Tier-3s, but also other small sites that want to participate in OSG but may not have the ability to put in large amounts of administrator time,” said Fraser. “Every time we make things simpler, it lowers the barrier to more scientific groups either using the OSG or adopting the software for use on their own grids.”

—Miriam Boon, iSGTW