The LCG meets 1 GB/s challenge
On 15 February the Worldwide LHC Computing Grid collaboration (WLCG) officially announced the successful completion of a service challenge at the Computing for High-Energy and Nuclear Physics 2006 conference (CHEP '06) in Mumbai, India. The challenge involved sustaining a continuous flow of physics data on a worldwide Grid infrastructure at up to 1 GB/s. The maximum sustained data rates achieved correspond to transferring a DVD of scientific data from CERN every five seconds.
The data were transferred from CERN to 12 major computer centres worldwide. More than 20 other computing facilities were involved in successful tests of a global Grid service for real-time storage, distribution and analysis of the data. The completion of this service challenge is a key milestone on the way to establishing the necessary computing infrastructure for the LHC. The results represent a step forward from a previous service challenge in early 2005 that involved just seven centres in Europe and the US and achieved sustained rates of 600 MB/s.
• April 2006 p15 (abridged).
Worldwide Grid awaits LHC start-up
In January, almost 300 members of the Worldwide LHC Computing Grid (WLCG) collaboration attended a week-long workshop at CERN to discuss the status of the infrastructure, as well as detailed plans and timescales to prepare for the start-up of the LHC. The week included experiment-specific sessions and a joint-operations workshop.
The WLCG was formed by resource providers – Grid projects, mainly EGEE in Europe and OSG in the US, and individual resource providers – to deal with the 15 PB of LHC data expected every year. The computing sites are arranged in a number of tiers, with CERN serving as the Tier-0 site, which will collect and distribute data to 12 Tier-1 sites (p67). Some 150 Tier-2 sites will help process the data.
All four large LHC experiments organized sessions to allow direct contact between site managers and experiments experts. The ALICE session concentrated on different tutorials regarding specific aspects of ALICE software such as monitoring, AliRoot and AliEn. Topics in the ATLAS session included data management, storage-resource management and the security model of the services deployed.
The CMS session covered file-transfer and integration plans as well as computing resources and storage classes. Discussions in the LHCb session included topics such as testing of the "glexec" middleware module by some sites, data security and data transfer between sites.
Three working groups have been set up to focus on improving service and site reliability, which are all coordinated. The Grid Monitoring Group will pull together monitoring data and provide views for the different stakeholders. The Site Management group will work to harmonize tools and best practices and will issue recommendations to improve site management. The System Analysis group will continue work done by ARDA to provide feedback from the applications point of view. Another area still under development is the interoperation between the EGEE and OSG infrastructures.
• For more information, videos and the presentations, see http://indico.cern.ch/conferenceDisplay.py?confId=3738.
• April 2007 p13 (abridged).