Grid computing involves distributing computing resources across a network to tackle large problems. The Worldwide LHC Computing Grid (WLCG) was established to support the Large Hadron Collider (LHC) experiment, which produces around 15 petabytes of data annually. The WLCG uses a four-tiered model, with raw data stored at Tier-0 (CERN), copies distributed to Tier-1 data centers, computational resources provided by Tier-2 centers, and Tier-3 facilities providing additional analysis capabilities. This distributed model has proven effective in supporting the first year of LHC data collection and analysis through globally shared computing resources.

1. GRID COMPUTING &IT’S
APPLICATIONS / LHC GRID
Alokeparna Choudhury
Stream. CSE
Roll No. 20091005
Reg. No. 2783 of 2009-10
University Institute of Technology

2. INTRODUCTION TO
GRID COMPUTING

3. WHAT IS GRID?
 In Grid computing the word “GRID” comes from the concept
“Grating of crisscrossed parallel bars”
 Grid is a network of horizontal and perpendicular lines,
uniformly spaced by means of a system of coordinates.
 In grid computing the computing data and resources are
implementing in a GRID network.

4. WHY DO WE NEED GRIDS?
Many large-scale problems cannot be solved by
a single computer
Globally distributed data and resources

5. 5
GRID ARCHITECHTURE

6. CONTD.
 The architecture for grid computing systems consists of four layers.
 The lowest fabric layer provides interfaces to local resources at a
specific site.
 The connectivity layer consists of communication protocols for
supporting grid transactions.
 In addition the connectivity layer will contain security protocols to
authenticate users and resources.
 The resource layer is responsible for managing a single resource.
 The collective layer deals with handling access to multiple
resources.
 It typically consists of services for resource discovery, allocation
and scheduling of tasks onto multiple resources.
 Finally , the application layer consists of the applications that
operate within a virtual organization and which make use of the grid
computing environment.

7. FROM GRIDS TO CLOUD
COMPUTING
• Logical steps:
– Make the grids public
– Provide much simpler interfaces (and more limited
control)
– Charge usage of resources
 However, the promise of cloud computing finds a great user
base in science grids due to:
– Intense computations
– Huge amounts of storage needs

8. CONTD.
 Much of the Grid research community is now working on
clouds.
 It is quite feasible to have a cloud within a computational grid,
as it is possible to have a computational grid as a part of a
cloud.
 In a computational grid, one large job is divided into many
small portions and executed on multiple machines. This
characteristics is fundamental to a grid, not so in a cloud.

9. SOME GRID APPLICATIONS
Distributed supercomputing
High-throughput computing
On-demand computing
Data-intensive computing
Collaborative computing

10. INTRODUCTION TO LCG
 The LHC Computing Grid(LCG) was approved by the CERN
council on 20th September 2001 to develop, build and maintain
a distributed computing infrastructure for the storage &
analysis of data from the 4 LHC experiments.
 The project was defined with 2 distinct phases.
 In Phase 1(2002-2005) the required s/w & services would be
developed & prototyped.
 In Phase2(2006-2008) the initial services for the 1st beams
from the LHC machine would be constructed & brought into
operation.

11. WLCG
 Worldwide LHC Computing Grid
--Distributed Computing Infrastructure for LHC experiments
 Linking 3 distributed infrastructures
-OSG Open Science Grid in the US
-EGI European Grid Infrastructure
-NDGF Nordic Data Grid Facility
 Linking more than 300 computer centers
 Providing > 340,000 cores
 To more than 2000(active) users
 Moving ~10GB/s for each experiment
 Archiving 15PB per year

13. THE LHC WITH GRID
COMPUTING
 The Large Hadrons Collider(LHC),
starting to operate in 2007, will
produce roughly 15 Pet bytes(15
million GB) of data annually.
 The mission of the LHC Computing
Grid (LCG) project is to build &
maintain a data storage and analysis
infrastructure for the entire high
energy physics community that will
use the LHC.

14. CONTD.
 In the case of the LHC , a novel globally distributed
model for data storage and analysis-a computing grid-was
chosen to centralize all of this capacity at one
location near the experiments.
 The LCG Project will implement a grid to support the
computing models of the experiments using a distributed
four-tiered model.

15. TIER-0
 The original raw data emerging from the data
acquisition systems will be recorded at the Tier-0
centre at CERN.
 The maximum aggregate bandwidth for raw data
recording for a single experiment(ALICE) is 1.25GB/s.
 ALICE is A Large Ion Collider Experiment and is
prepared for CERN’s Large Hadrons collider. It
concerns with the Grid Computing technologies,
needed to analyze ALICE data.

16. CONTD.
 The first-pass reconstruction will take place at the Tier-0,
where a copy of the reconstructed data will be stored.
 The tier-0 will distribute a second copy of the raw data
across the Tier-1 centre associated with the experiment.
 Additional copies of the reconstructed data will also be
distributed across the Tier-1 centre according to the
policies of each experiment.

18. TIER-1
 The role of the Tier-1 center varies according to the
experiment, but in general they have the prime responsibility
for managing the permanent data storage-raw, simulated and
processed data.
 It provides computational capacity for reprocessing and for
analysis process that require access to large amounts of data.
 At present 11 Tier-1 centers have been defined, most of them
serving several experiments.

19. TIER-2
 The role of the Tier-2 centers is to provide computational
capacity and appropriate storage services for Monte Carlo
event simulation and for end user analysis.
 The Tier-2 centers will obtain data as required from Tier-1
centers, and the data generated at Tier-2 will be sent to Tier-1
for permanent storage.
 More than 100 Tier-2 centers have been identified.

22. TIER-3
 Other computing facilities in universities and
laboratories will take part in the processing and
analysis of LHC data as Tier-3 facilities.
 These lie outside the scope of the LCG project,
although they must be provided with access to the
data and analysis facilities as decided by the
experiments.

24. As part of WLCG there are 2 “Tier-2” sites in India:
TIFR in Mumbai and VECC in Kolkata
KOLKATA TIER-2

25. SUMMARY
 Grid Computing and WLCG has proven itself during the first
year of data-taking of LHC.
 Grid Computing works for WLCG community and has a
future.
 Long term sustainability will be a challenge.
FUTURE
 Stable WANs will provide excellent performance and move to
a less hierarchical model.
 Virtualization and cloud computing.
 Moving towards standards.
 Integrating new technology.

26. RREEFFEERREENNCCEESS
 https://openlab-mu-internal.web.cern.ch
 cg-archive.
web.cern.ch/lcg.../lhcgridfest/.../Robertson
_Les_GridFest.pdf
 scientific-journals.
org/journalofsystemsandsoftware/.../vol2
no5_4.pdf
 edutechwiki.unige.ch/en/Grid_computing
 www.redbooks.ibm.com/redbooks/pdfs/sg246778.
pdf
 Distributed Systems-principles and paradigms-
Andrew S. Tanenbaum , Maarten Van Steen