Porting Scientific Applications on GRID: CERN Experience

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Enabling Grids for E-sciencE

www.eu-egee.org

Porting Scientific Applications on GRID: CERN ExperiencePatricia Méndez Lorenzo

CERN (IT-PSS/ED)

Trieste, 10th February 2006

ICTP/INFM-Democritos Workshop on Porting Scientific Applications on Computational GRIDs

Trieste, 10th February 2006 Patricia Méndez Lorenzo


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Outlook

◘ This is an introductory presentation

◘ Let’s see what is CERN, what is LCG, the elements, the actors and how to get involved

◘ This afternoon, during the 2nd talk we will see some practical examples of communities getting involved in the GRID



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CERN

The European Organization for Nuclear ResearchThe European Laboratory for Particle Physics

◘ Fundamental research in particle physics◘ Designs, builds &operates large accelerators

◘ Financed by 20 European countries (member states) + others (US,

Canada, Russia, India, etc)2000 staffs + 6000 users from all over the

world

◘ Next huge challenge: LHC (starts in 2007) experiment: 2000 physicists, 150 universities, with an operation life greater than 10 years



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LHC- Physics Goals

◘ Higgs particle Key particle in the Standard Model that could explain the elementary particle masses

◘ Search for super-symmetric particles and possible extra dimensionsTheir discovery would be a serious push for Super Symmetric theories or “String Theories” aiming at the unification of the fundamental forces in the Universe

◘ Anti-matter issuesWhy the Universe is made of matter instead of an equal quantity of matter and antimatter

◘ Understand the early Universe (10 -20 – 10-6 seconds)Soup of quarks and gluons stabilized into nucleons and then nuclei and atoms



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The LHC Experiment

The LHC: Generation of 40 million particle collisions (events) per second

at the center of each for experiments

Reduce by online computers that filter out

a few hundred good events per sec

Recorded on disk and magnetic tape

at 100-1000 MB/sec: 15 PB/year

ALICE, ATLAS, CMS

and LHCb



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The LHC Computing Environment

LCG (LHC computing Grid) has been developed to build and maintain a storage and analysis infrastructure for the

entire high-energy physics community

◘ LHC is beginning the data taking in summer 2007➸ Enormous volume of data

• Few PB/year at the beginning of the machine operation• Several hundred PB yearly produced for all experiments in 2012

➸ Large amount of processing power ◘ As a solution a LCG world-wide Grid is proposed

➸ Established using a world-wide distributed federal Grid➸ Many components, services, software, etc, to coordinate

◘ Takes place at an unprecedented scale➸ Many institutes, experiments and people working closely together

◘ LCG must be ready at full production capacity, functionality and reliability in less than 1 year!

LCG is an essential part of the chain allowing the physicists to perform their analyses

➸ It has to be a stable, reliable and easy to use service



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LCG: The LHC Computing Grid

Tier-0 – the accelerator centreData acquisition and initial

Processing of raw dataDistribution of data to the different

Tier’s

Canada – Triumf (Vancouver)France – IN2P3 (Lyon)Germany – Forschunszentrum KarlsruheItaly – CNAF (Bologna)Netherlands – NIKHEF/SARA (Amsterdam)Nordic countries – distributed Tier-1

Spain – PIC (Barcelona)Taiwan – Academia SInica (Taipei)UK – CLRC (Oxford)US – FermiLab (Illinois) – Brookhaven (NY)

Tier-1 – “online” to the data acquisition process high availabilityManaged Mass Storage – grid-enabled data serviceData-heavy analysisNational, regional support

Tier-2 – ~100 centres in ~40 countriesSimulation

End-user analysis – batch and interactive



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LCG in the World

May 2005140 Grid sites

34 countries

12000 CPUs

8 PetaBytes

30 sites3200 cpus

25 Universities4 National Labs2800 CPUs

Grid3



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What is the structure we have at CERN?

◘ CERN is the T0

➸ Deployment: We pack and distribute the software to the sites

➸ Development: Development of new projects and also part of the software

➸ Support: Assistance to experiments and sites

EXPERIMENTS

SITES

LCG DEPLOYMENT

ARDA

EIS APPLICATIONS

Contact through ARDA-EIS



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Our Tier1 centers

ALICE ATLAS CMS LHCb

1 GridKa Karlsruhe Germany X X X X

2 CCIN2P3 Lyon France X X X X

3 CNAF Bologna Italy X X X X

4 NIKHEF/SARA Amsterdam Netherlands X X X

5 NDGF Distributed Dk, No, Fi, Se X X

6 PIC Barcelona Spain X X X

7 RAL Didcot UK X X X X

8 TRIUMF Vancouver Canada X

9 BNL Brookhaven X

10 FNAL Batavia X

11 ASCC Taipei X X



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The Elements of the Middleware

UI UI

CE

RB/BDII

SE

WN

WN

WN

WN

WN

WN

LFC

Connections to UI

Resources Searching

Sent to th

e batc

h

system Distribution to CPUs

Ouputs copied to

Storage Resources

Catalogs getting track of the inputs



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Current status of the Experiments and the GRID

◘ They have to get ready

➸ How to take raw data and how

to store and distribute them

➸ How to produce simulated data

➸ How to analyze data

◘ They are not alone,

EGEE/LCG assist them➸ ARDA Group

➸ Application area Group

Successfully completed 6 months before the data taking

They have to be ready to a high stability level

Ramp up their capacity to twice the nominal data rates expected for the production phase

EXPERIMENTS SITES

SERVICES: EGEE/LCG

THIS IS A FULL CHALLENGE

FOR ALL OF US

THE SUPPORT AMONG THE

3 ACTORS IS FUNDAMENTAL



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We have a fundamental Challenge in front of us:

Service ChallengeAs we have just seeing experiments and Grid teams are ramping up… but making what exactly?

Service Challenges (SC): Grid part ◘ We provide services to the users (done) ◘ But we have to test them to the necessary level of functionality, reliability and scale ◘ We are preparing, hardening and delivering the production of the LCG environment ◘ Moreover we have to run an environment as realistic as possible

Data Challenges (DC): Experiments part ◘ Experiments test their LCG based production chains and performance of the Grid fabric

➸ Processing data from simulated events➸ Emulating step by step the scale they will have to face during real data taking

◘ From 2005 experiments include SC testing as part of their DC



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Assistance to Experiments

ARDA: A Realization of Distributed Analysis for LHC

◘ Main Goal: ➸ Coordination of activities needed to prototype distributed analysis systems for the LHC➸ It does NOT develop middleware, go one step further, closer to the users

◘ Main Actors:➸ People of each experiment (they know what they need)➸ Middleware development team (they know what they have)➸ Experiment support team: EIS (they can contact both)

◘ New Gridifications:➸ Coordinated by this group (You will go through us, surely)➸ Application of their tools to new communities (We can help you)



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OK, now you know the project, its elements and its actors

And however you want still to

go inside… ☺Good choice, let’s see

how



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New Contributions

◘ Several different communities are joining the GRID project◘ It has applications to all these fields needing large amount of computational and space resources

◘ We are direct supporting (outside LHC exp.):

➸ Biomed (medical applications)

➸ Geant4 (simulation toolkit)

➸ UNOSAT, ITU (UNO projects)

◘ And how to put then inside the EGEE/LCG is a HOT TOPIC at this moment

This afternoon

Next part of this 1st talk



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Before proceeding…

◘ There are several points under discussion at this moment about how to admit new Virtual Organizations arriving to the GRID

➸ Last discussion, during the Grid Deployment Board meeting this Wednesday

◘ I going to explain the procedure if the request is associated in somehow with CERN

➸ This is my experience

◘ What to do in the rest of cases is being discussed➸ It should have maximal priority inside the EGEE environment

➸ From my point of view it must be flexibly ➸ I will explain you also my proposal



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What we are doing now for Geant4

◘ Full Geant4 gridification this afternoon◘ Right now, just see it as a new community…◘ But a “special” community because: ➸ They pretend to run twice per year (Not the whole year)

► To validate their own software

➸ It is used as simulation tool by many Grid VOs► A good validated product, will make experiments life easier

➸ Its software is very well known ► stable, reliable, quite long tested► LCG thought to use this software as a part of the LCG test

➸ The tests inside LCG were asked by people placed at CERN► Geant4 at CERN, LCG support at CERN, easier to gridify and support this community



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Immersion of Geant4 in LCG

◘ As any other new VO, they will need support➸ Provided by EGEE/LCG

◘ Support is fundamental➸ To involve you quickly and safely ➸ Till you gain familiarity it will play the role of software, production and VO manager➸ We dial with the site on your behalf

◘ They will need to gain familiarity with the system and to test it before passing through the whole EGEE/LCG VO procedure➸ You have to learn before taking a decision➸ This will be a situation to face more and more

UNOSAT and more

◘ EGEE/LCG has to face:➸ What to do with light new VOs arriving ➸ The solution should not be “dteam” (deployment team VO)➸The most important point is already setup: YOU HAVE SUPPORT



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Our Challenge

Provide a formal procedure to give them support

◘ It is not the same if the community contacts directly the support at CERN◘ This should not be like that and a common policy should be found

➸ A regional policy delegation could be the solution ◘ Most of all in terms of VO policy a procedure should be fixed◘ Something we still have to clarify

➸ Are the sites free enough to provide resources to any new VO as local users?

► Well, this is what we have done for Geant4 and this does seem the method to follow



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Current Procedure

2) EGAAP

3) NA4/SA14) CICs/ROCs

Init

ial

dep

loym

ent

con

fig

ura

tio

n

Asks for change

Recommended VO candidate

Resource proposal

VO requirements

1) New applications

Geant4 application

Sites

1. Geant4 is quite known

2. It is fully supported

3. It was the 3rd production

4. We had a short time to begin the production

EGEE

ProcedureLC

GP

roce

dure

Wha

t we

did

The solution for us is to begin the support here



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What we have done

◘ We presented the Geant4 community last GDB and we asked for local support

➸ In my ideal world, once you ask for the entry a support person should be assigned to you to discuss with you your hopes and the viability

➸ Let him to deal with the LCG/Sites Management ◘ At the same time we were following the official procedure to become VO ➸ After testing the product and seeing you want it, this is mandatory

◘ In the case of Geant4 ➸ We asked directly for the support to Geant4 site per site ➸ We got in time in 5 sites ➸ We got the total amount of CPUs required for Geant4 (120CPUs)

➸ LCG Efficiency: 99% ➸ At any moment the Geant4 production was totally followed not to interfere in

a wrong way with the sites► This is fundamental for the sites► Your LCG support is responsible of your production► Many other communities are running and you should not interfere them (and they should not interfere you!)



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Light-weight VO registration

◘ We are considering to have an incubator VO to assist new communities

➸ This VO is standard for all new communities ➸ It allows you to play with the system

➸ During this time your support plays with you ➸ You do not decide the policy of this VO, we do it ➸ You will not make productions inside, you just learn ➸ LCG has already experience, we know how to deal with

◘ Warning: You should have a limited time inside ➸ Then you are a integrated VO ➸ You should go through the registrations steps ➸ Now your support makes exactly that: LCG support no more, no less

► With a strict LCG support no problems should be seen► Experiments happy, sites happy, LCG happy



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Final Message

LCG was born with a clear objective

Assist LHC experiments during their real data taking

The project is however extensible and quite attractive for any other community

We are thinking at this moment how to procede with the light-weight VOs

This is foreseen and it is part of the project

SUPPORT is the most important point if you arrive to the GRID... And the infrastructure is already developed

Documents

Porting Scientific Applications on GRID: CERN Experience