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The ATLAS Computing Model Eric Lançon SaclayLCG-France Lyon 14-15 Dec. 2005.

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Presentation on theme: "The ATLAS Computing Model Eric Lançon SaclayLCG-France Lyon 14-15 Dec. 2005."— Presentation transcript:

1 The ATLAS Computing Model Eric Lançon SaclayLCG-France Lyon Dec. 2005

2 Workshop LCG-France E. lancon 2 Overview The ATLAS Facilities and their rolesThe ATLAS Facilities and their roles Growth of resourcesGrowth of resources CPU, Disk, Mass Storage Network requirementsNetwork requirements CERN  Tier 1  Tier 2 Data & Service challengesData & Service challenges

3 Workshop LCG-France E. lancon 3 Computing Resources Computing Model fairly well evolved, but still being revisedComputing Model fairly well evolved, but still being revised Documented in:http://doc.cern.ch//archive/electronic/cern/preprints/lhcc/public/lhcc pdfhttp://doc.cern.ch//archive/electronic/cern/preprints/lhcc/public/lhcc pdf There are (and will remain for some time) many unknownsThere are (and will remain for some time) many unknowns Calibration and alignment strategy is still evolving Physics data access patterns MAY start to be exercised this Spring Unlikely to know the real patterns until 2007/2008! Still uncertainties on the event sizes, reconstruction time Lesson from the previous round of experiments at CERN (LEP)Lesson from the previous round of experiments at CERN (LEP) Reviews in 1988 underestimated the computing requirements by an order of magnitude!

4 Workshop LCG-France E. lancon 4 ATLAS Facilities Event Filter Farm at CERN (pit)Event Filter Farm at CERN (pit) Located near the Experiment Assembles data into a stream to the Tier 0 Center Tier 0 Center at CERN (comp. center)Tier 0 Center at CERN (comp. center) Raw data  Mass storage at CERN and to Tier 1 centers Prompt reconstruction producing Event Summary Data (ESD) and Analysis Object Data (AOD) Ship ESD, AOD to Tier 1 centers Tier 1 Centers distributed worldwide (approximately 10 centers)Tier 1 Centers distributed worldwide (approximately 10 centers) Re-reconstruction of raw data, producing new ESD, AOD Tier 2 Centers distributed worldwide (approximately 30 centers)Tier 2 Centers distributed worldwide (approximately 30 centers) Monte Carlo Simulation, producing ESD, AOD ESD, AOD  Tier 1 centers Physics analysis CERN Analysis FacilityCERN Analysis Facility Tier 3 Centers distributed worldwideTier 3 Centers distributed worldwide Physics analysis

5 Workshop LCG-France E. lancon 5 Processing Tier-0:Tier-0: First pass processing on express/calibration physics stream hours later, process full physics data stream with reasonable calibrations  These imply large data movement from T0 to T1s Tier-1:Tier-1: Reprocess 1-2 months after arrival with better calibrations Reprocess all resident RAW at year end with improved calibration and software  These imply large data movement from T1 to T1 and T1 to T2

6 Workshop LCG-France E. lancon 6 Processing cont’d Tier-1:Tier-1: 1/10 of RAW data and derived samples Shadow the ESD for another Tier-1 (e.g. 2/10 of whole sample) Full AOD sample Reprocess 1-2 months after arrival with better calibrations (to produce a coherent dataset) Reprocess all resident RAW at year end with improved calibration and software Provide scheduled access to ESD samples Tier-2sTier-2s Provide access to AOD and group Derived Physics Datasets Carry the full simulation load

7 Workshop LCG-France E. lancon 7 Analysis Model Analysis model broken into two components Scheduled central production of augmented AOD, tuples & TAG collections from ESD  Derived files moved to other T1s and to T2s Chaotic user analysis of augmented AOD streams, tuples, new selections etc and individual user simulation and CPU-bound tasks matching the official MC production  Modest job traffic between T2s

8 Workshop LCG-France E. lancon 8 Inputs to the ATLAS Computing Model (1)

9 Workshop LCG-France E. lancon 9 Inputs to the ATLAS Computing Model (2)

10 Workshop LCG-France E. lancon 10 Data Flow from experiment to T2s T0 Raw data  Mass Storage at CERNT0 Raw data  Mass Storage at CERN T0 Raw data  Tier 1 centersT0 Raw data  Tier 1 centers 1/10 in each T1 T0 ESD  Tier 1 centersT0 ESD  Tier 1 centers 2 copies of ESD distributed worldwide 2/10 in each T1 T0 AOD  Each Tier 1 centerT0 AOD  Each Tier 1 center T1  T2T1  T2 Some ESD, ALL AOD? T0  T2 Calibration processing?T0  T2 Calibration processing? Dedicated T2s for some sub-detectors

11 Workshop LCG-France E. lancon 11 Total ATLAS Requirements in for 2008

12 Workshop LCG-France E. lancon 12 Important points Storage of Simulation data from Tier 2’sStorage of Simulation data from Tier 2’s Assumed to be at T1s Need partnerships to plan networking Must have fail-over to other sites? CommissioningCommissioning These numbers are calculated for the steady-state but with the requirement of flexibility in the early stages Simulation fraction is an important tunable parameter in T2 numbers!Simulation fraction is an important tunable parameter in T2 numbers! Simulation / Real Data = 20% in TDR Heavy Ion running still under discussion.Heavy Ion running still under discussion.

13 Workshop LCG-France E. lancon 13 ATLAS T0 Resources

14 Workshop LCG-France E. lancon 14 ATLAS T1 Resources

15 Workshop LCG-France E. lancon 15 ATLAS T2 Resources

16 Workshop LCG-France E. lancon 16 Offres / T1 2008

17 Workshop LCG-France E. lancon 17 Tier 1  Tier 2 Bandwidth The projected time profile of the nominal aggregate bandwidth expected for an average ATLAS Tier- 1 and its three associated Tier-2s.

18 Workshop LCG-France E. lancon 18 Tier 1  CERN Bandwidth The projected time profile of the nominal bandwidth required between CERN and the Tier-1 cloud.

19 Workshop LCG-France E. lancon 19 Tier 1  Tier 1 Bandwidth The projected time profile of the nominal bandwidth required between T1 and Tier-1.

20 Workshop LCG-France E. lancon 20 Conclusions Computing Model Data Flow understood for placing Raw, ESD and AOD at Tiered centersComputing Model Data Flow understood for placing Raw, ESD and AOD at Tiered centers Still need to understand data flow implications of Physics Analysis How often do you need to “back navigate” AOD to ESD? How distributed is Distributed Analysis? Some of these issues will be addressed in the upcoming (early 2006) Computing System Commissioning exercise.Some of these issues will be addressed in the upcoming (early 2006) Computing System Commissioning exercise. Some will only be resolved with real data in Some will only be resolved with real data in

21 Workshop LCG-France E. lancon 21 Key dates for Service Preparation SC3 LHC Service Operation Full physics run First physics First beams cosmics Sep05 - SC3 Service Phase May06 –SC4 Service Phase Sep06 – Initial LHC Service in stable operation SC4 SC3 – Reliable base service – most Tier-1s, some Tier-2s – basic experiment software chain – grid data throughput 1GB/sec, including mass storage 500 MB/sec (150 MB/sec & 60 MB/sec at Tier-1s) SC4 – All Tier-1s, major Tier-2s – capable of supporting full experiment software chain inc. analysis – sustain nominal final grid data throughput (~ 1.5 GB/sec mass storage throughput) LHC Service in Operation – September 2006 – ramp up to full operational capacity by April 2007 – capable of handling twice the nominal data throughput Apr07 – LHC Service commissioned

22 Workshop LCG-France E. lancon 22 Data Challenges

23 Workshop LCG-France E. lancon 23 Statistics on LCG usage Assez loin des ambitions Bcp de problèmes techniques au démarrage Vers la fin 10% de LCG au CC In2p3 = Clermont + Lyon jobs

24 Workshop LCG-France E. lancon 24 SC3 : T0->T1 exercise T0 - T1 dataflow SC3 ATLAS

25 Workshop LCG-France E. lancon 25 Distributed Data Management (DDM) Catalogues généraux centralisés (LFC):Catalogues généraux centralisés (LFC): Contenus des datasets (1 dataset = plusieurs fichiers) Localisation des datasets dans les sites (T0-T1-T2) Liste des requêtes de transferts des datasets, etc… Catalogues locaux (LFC)Catalogues locaux (LFC) Localisation dans le site des fichiers de chaque dataset Site prend en charge à travers des agents (VOBox) :Site prend en charge à travers des agents (VOBox) : Récupération auprès du catalogue central de la liste des datasets et des fichiers associés à transférer Gestion du transfert Enregistrement des informations dans les catalogues locaux et centraux

26 Workshop LCG-France E. lancon 26 Pb : cron n’est pas géré par utilisateur grille DDM au CC 1 serveur dCache1 serveur dCache 2 pools de chacun 1-2 TB + Driver de bande : 40 MB/s Transfert par FTS (Geant 1 Gb/s)Transfert par FTS (Geant 1 Gb/s) A quand 10 Gb/s? VOBox LCG mode-CCIN2P3VOBox LCG mode-CCIN2P3 Machine Linux SL3 Catalogue LFC Serveur FTS (futurs transferts T1-T1 ou T1-T2) Certificats Grille Accès gsissh Soft DDM installé Pas besoin d'accès ROOT Peut être installé depuis le CERN

27 Workshop LCG-France E. lancon 27 Services challenges

28 Workshop LCG-France E. lancon 28 Integrated TB transfered

29 Workshop LCG-France E. lancon 29 Backup Slides

30 Workshop LCG-France E. lancon 30 From LATB…

31 Workshop LCG-France E. lancon 31 Heavy Ion Running

32 Workshop LCG-France E. lancon 32 Preliminary Tier-1 Resource Planning Capacity at all Tier-1s in 2008

33 Workshop LCG-France E. lancon 33 Preliminary Tier-2 Resource Planning Capacity at all Tier-2s in 2008 Includes resource planning from 27 centres/federationsIncludes resource planning from 27 centres/federations 11 known Tier-2 federations have not yet provided data11 known Tier-2 federations have not yet provided data These include potentially significant resources: USA CMS, Canada East+West, MPI Munich …..

34 Workshop LCG-France E. lancon 34 ‘Rome’ production : French sites

35 Workshop LCG-France E. lancon 35 ‘Rome’ production : Italian sites

36 Workshop LCG-France E. lancon 36 Distributed Data Management (DDM) Eviter l’utilisation d’un catalogue plat complètement centraliséEviter l’utilisation d’un catalogue plat complètement centralisé Organisation hiérarchique des catalogues de donnéesOrganisation hiérarchique des catalogues de données Dataset= Collection de fichiers Datablock : Collection de datasets Etiquetage des datasets pour maintenir une complète consistence Information de chaque fichier physique stockée localementInformation de chaque fichier physique stockée localement Mouvements de données par datasetMouvements de données par dataset Mouvement vers un site déclenché par une souscription à travers un programme clientMouvement vers un site déclenché par une souscription à travers un programme client


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