What is a Grid?
A Grid is a way of connecting computers together to allow the sharing of both computer processing power and data storage. A user may submit a job, and software (called middleware) will check the users credentials and find a suitable computer on which to run the job. This computer may be anywhere in the world, provided it is part of the grid infrastructure to which the user has submitted the job. More explanation of what a Grid is is available at the CERN Grid Cafe (link opens in a new window).
The Large Hadron Collider LHC (link opens in a new window) at CERN near Geneva is the largest scientific intstrument on the planet. When it is operating it will produce roughly 15 Petabytes (15 million Gigabytes) of data annually which thosands of scientists around the world need to access and analyse. Grid Computing was chosen as the solution for the analysis of LHC data by the Particle Physics community. The Particle Physics Department was instrumental in this decision from the beginning and has continued to play a major role in the management, development, deployment and maintenance of Grid technology.
Within the UK most of the work is carried out as part of the UK Computing for Particle Physics GridPP (link opens in a new window) project and the Enabling Grids for EsciencE EGEE (link opens in a new window) project, which is now in it's 3rd phase, EGEE-III.
Grid middleware developement
Grid middleware is the software which turns networks of computers into grids, as it allows users to submit their data to the Grid for analysis, and manages the distribution of jobs and data around the grid.
A team of people in the Particle Physics Department has been developing R-GMA (link opens in a new window), the Relational Grid Monitoring Architecture, which is an information, monitoring and logging service for a distributed computing environment.
The department also contributes to the EGEE Integration, Testing and Certification activity, SA3.
The Worldwide LHC Computing Grid WLCG (link opens in a new window) project is building and maintaining a data storage and analysis infrastructure for the entire high energy physics community that will use the LHC.
The data from the LHC experiments will be distributed around the globe, according to a four-tiered model. A primary backup will be recorded on tape at CERN, the "Tier-0" centre of WLCG. After initial processing, this data will be distributed to a series of Tier-1 centres, large computer centres with sufficient storage capacity and with round-the-clock support for the Grid. The Tier-1 centres will make data available to Tier-2 centres, each consisting of one or several collaborating computing facilities, which can store sufficient data and provide adequate computing power for specific analysis tasks. Individual scientists will access these facilities through Tier-3 computing resources, which can consist of local clusters in a University Department or even individual PCs, and which may be allocated to LCG on a regular basis.
GridPP is building a distributed computing Grid across the UK primarily for the use of particle physicists, this forms the UK part of the WLCG. In the United Kingdom there are 4 Tier 2 faciliites, Northgrid, Southgrid, Scotgrid and London Grid. The Particle Physics Department hosts SouthGrid facilities: which is distributed between the Universities of Bristol, Birmingham, Cambridge and Oxford and the Rutherford Appleton Laboratory. The department is also one of 17 Tier 3 facilities within the United Kingdom. Staff in the Particle Physics department also contribute to the deployment and support for the UK Tier 1 centre (link opens in a new window) at RAL.
In any computing system security is an important concern. In the Grid environment, security poses some aditional problems. In EGEE the Security Co-ordination Group SCG (link opens in a new window) is responsible for the overall security co-ordination.
The EGEE Grid Security Vulnerability Group GSVG (link opens in a new window), and The EGEE/WLCG Joint Security Policy Group JSPG (link opens in a new window) are co-funded by EGEE and GridPP, and are lead by members of the Particle Physics Department.
Management, documentation and user support
Members of the Particle Physics department are part of the management boards on both the EGEE-III project and GridPP project.
User support is another activity carried out by the department, through contribution to the EGEE User Communtity Expansion and Support NA4 (link opens in a new window) activity, as well as Tier 1 co-ordinators for ATLAS, CMS and LHb. The User Board Chair is also in the department.
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