Predrag Buncic

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Predrag Buncic Institut fuer Kernphysik,
Frankfurt CERN For ALICE Collaboration
The AliEn system, status perspective
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Talk Outline

• Alice Computing model
• AliEn
• Project timeline
• Architecture
• Components
• File Catalogue and Resource broker
• Outlook
• Conclusions

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ALICE _at_ CERN LHC

• Typical next generation HEP experiment
• 1000 scientists in 100 of institutions
• CPU data intensive simulation reconstruction
  
• Results in need for heavily distributed
  processing and event storage
• Complex analysis of distributed data
• Large files (one simulated event up to 2GB)
• Specific to Alice heavy ion events (but, we have
  to plan for 1PB/year of pp data as well)
• Many files
• 109 files/year (x n, ngt2)
• 2 PB/year

• AliEn (ALIce ENvironment) is our attempt to
  gradualy approach and tackle computing problems
  at LHC scale and implement ALICE Computing Model

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ALICE Computing Model
Nice! I only have to learn C

• Typical HEP use cases
• Simulation Reconstruction
• Event mixing
• Analysis

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Project Timeline
Functionality
Interoperability
Performance, Scalability, Standards
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4 continents, 32 sites
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AliEn V.O.
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What is AliEn?

• Main features
• Distributed file catalogue built on top of RDBMS
• File replica and cache manager with interface to
  MSS
• CASTOR,HPSS,HIS
• AliEnFS Linux file system that uses AliEn File
  Catalogue and replica manager
• SASL based authentication which supports various
  authentication mechanisms (including
  Globus/GSSAPI)
• Resource Broker with interface to batch systems
• LSF,PBS,Condor,BQS,
• Various user interfaces
• command line, GUI, Web portal
• Package manager (dependencies, distribution)
• Metadata catalogue
• C/C/perl/java API
• ROOT interface (TAliEn)
• SOAP/Web Services
• EDG compatible user interface
• Common authentication

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AliEn Architecture
AliEn Core Components services
Interfaces
External software
Database Proxy
ADBI
User Application
File Metadata Catalogue
API (C/C/perl)
LDAP
Authentication
RB
FS
External Libraries
User Interface
Perl Core
Perl Modules
CE
Config Mgr
CLI
SOAP/XML
V.O. Packages Commands
SE
GUI
Package Mgr
Web Portal
()
Logger
Low level
High level
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AliEn Components
Web of AliEn Services
Modules libraries
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File catalogue
If you're a programmer, one of the great things
about Linux and Unix is that everything is a file
-- or at least acts like one. From devices to
sockets, the "everything is a file" paradigm has
served Unix well for a long, long time.
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Resource Broker
Pull instead of traditional Push architecture
Authen
Broker
TransferBroker
TransferOptimiser
Logger
IS
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GRID of GRIDs?
AliEn User Interface
Nice! Now I do not have to worry about ever
changing GRID environment
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Outlook

• Support for analysis/PROOF interface (gt A.Peters
  )
• Seamless access to GRID resources from ROOT
  prompt
• AliEnFS
• gt AliEnFS - a Linux File system for the AliEn
  Grid services (A. Peters)
• EDG interface
• gt AliEn - EDG interoperability in ALICE (poster)
• Optimization
• Queue optimizers
• Query optimization and caching
• Service registration/discovery using P2P
  technology
• Jabber XML based instant messaging protocol
• AliEn Web Services gt OGSI Grid services
• Monitoring, modeling and simulation of AliEn GRID
• MonALisa framework
• Virtual datasets?

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Conclusions
2001 2002
2003 2004 2005

• After only 2 years of development, we have
  deployed a distributed computing environment
  which meets the needs of Alice experiment
• Simulation Reconstruction
• Event mixing
• Analysis
• Using Open Source components (representing 99
  of the code), internet standards (SOAP,XML, PKI)
  and scripting language (perl) was the key element
  that alllowed quick prototyping and very fast
  development cycles
• We are now very close to finalizing AliEn
  architecture and API
• OpenAliEn?

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CHEP 2003

• AliEn Resource Brokers (Pablo Saiz, poster)
• AliEnFS - a Linux File system for the AliEn Grid
  services (Andreas Peters)
• AliEn - EDG interoperability in ALICE (Stefano
  Bagniasco, poster)
• ALICE experience with EDG (Piergiorgo Cerello)
• The MammoGrid Project (Richard McClatchey, next
  talk)
• Use of HEP software for medical applications
  (Piergiorgo Cerello)