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The grid is set to grapple with large computations

30 May 2000

Particle physics has always pushed computing and
computing techniques to the limit – witness the World Wide
Web developed at CERN. Continuing this tradition, particle
physics at CERN will soon provide a crucial testbed for
even more powerful network-based information handling
systems – the Grid.

When CERN’s LHC collider begins operation in 2005, it
will be the most powerful machine of its type in the world,
providing research facilities for thousands of researchers
from all over the globe.

The computing capacity
required for analysing the data generated by these big LHC
experiments will be several orders of magnitude greater
than that used by current experiments at CERN, itself
already substantial. Satisfying this vast data-processing
appetite will require the integrated use of computing
facilities installed at several research centres across Europe,
the US and Asia.

During the last two years the
Models of Networked Analysis at Regional Centres for
LHC Experiments (MONARC) project, supported by a
number of institutes participating in the LHC programme,
has been developing and evaluating models for LHC
computing. MONARC has also developed tools for
simulating the behaviour of such models when
implemented in a wide-area distributed computing
environment.

This requirement arrived on the scene
at the same time as a growing awareness that major new
projects in science and technology need matching computer
support and access to resources worldwide.

In the
1970s and 1980s the Internet grew up as a network of
computer networks, each established to service specific
communities and each with a heavy commitment to data
processing.

In the late 1980s the World Wide Web
was invented at CERN to enable particle physicists
scattered all over the globe to access information and
participate actively in their research projects directly from
their home institutes. The amazing synergy of the Internet,
the boom in personal computing and the growth of the
Web grips the whole world in today’s dot.com
lifestyle.

Internet, Web, what
next?

However, the Web is not the end of the line. New
thinking for the millennium, summarized in a milestone
book entitled The Gridby Ian Foster of Argonne
and Carl Kesselman of the Information Sciences Institute of
the University of Southern California, aims to develop new
software (“middleware”) to handle computationsspanning
widely distributed computational and information resources
– from supercomputers to individual PCs.

In the
same way that the World Wide Web makes information
stored on a remote site immediately accessible anywhere on
the planet without the end user having to worry unduly
where the information is held and how it arrives, so the
Grid would extend this power to large computational
problems.

Just as a grid for electric power supply
brings watts to the wallplug in a way that is completely
transparent to the end user, so the new data Grid will do
the same for information.

Each of the major LHC
experiments – ATLAS, CMS and ALICE – is estimated to
require computer power equivalent to 40 000 of today’s
PCs. Adding LHCb to the equation gives a total equivalent
of 140 000 PCs, and this is only for day 1 of the
LHC.

Within about a year this demand will have
grown by 30%. The demand for data storage is equally
impressive, calling for some several thousand terabytes –
more information than is contained in the combined
telephone directories for the populations of millions of
planets. With users across the globe, this represents a new
challenge in distributed computing.

For the LHC,
each experiment will have its own central computer and
data storage facilities at CERN, but these have to be
integrated with regional computing centres accessed by the
researchers from their home
institutes.

CERN serves as Grid
testbed

As a milestone en route to this panorama, an
interim solution is being developed, with a central facility at
CERN complemented by five or six regional centres and
several smaller ones, so that computing can ultimately be
carried out on a cluster in the user’s research department.
To see whether this proposed model is on the right track, a
testbed is to be implemented using realistic
data.

Several nations have launched new
Grid-oriented initiatives – in the US by NASA and the
National Science Foundation, while in Europe particle
physics provides a natural focus for work in, among others,
the UK, France, Italy and Holland. Other areas of science,
such as Earth observation and bioinformatics, are also on
board.

In Europe, European Commission funding is
being sought to underwrite this major new effort to propel
computing into a new orbit.

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