ALICE Physics Data Challenge 04 P Hristov March

ALICE Physics Data Challenge’ 04 P. Hristov March 19, 2004 CERN 17 - 30 Sept. 2000 CERN School of Computing 1

Goals(http: //cern. ch/fca/ALICE-DCs. doc) ■ ■ ■ Determine readiness of the off-line framework for data processing Validate the distributed computing model PDC’ 2004: 10% test of the final capacity ■ ■ ■ Complete chain used for trigger studies Prototype of the analysis tools Comparison with parameterized MC Simulated RAW data PDC’ 04 physics: hard probes (jets, heavy flavours) & pp physics 19/03/2004 P. Hristov 2

Physics Data Challenge'2004 ■ ■ Simulation: 10^5 Pb-Pb + 10^7 p-p 102 TB ■ 450 KSI 2 K (~ tier-1 capacity) x 3 months ■ Distributed production, then data are shipped to CERN Reconstruction: 5 x 10^6 Pb-Pb+10^7 p-p 187 TB ■ Reconstruction is shared between CERN & outside centres according to available resources ■ Data originate from CERN Analysis: 5 x 10^6 Pb-Pb+10^7 p-p 13 TB See http: //aliweb. cern. ch/people/phristov/PDC 04. html 19/03/2004 P. Hristov 3

PDC’ 04 Strategy ■ Part 1: underlying events ■ ■ ■ Part 2: signal events & test of CERN as data source ■ ■ Distributed simulation, production of summable digits, digitization, clusterization, reconstruction, PID, and generation of ESD Data transfer to CERN: kinematics, track references, summable digits (hits for some detectors) Distributed simulation, production of summable digits, merging, digitization, clusterization, reconstruction, PID, generation of ESD Part 3: distributed analysis P. Hristov 19/03/2004 4

Ali. Root Layout G 3 G 4 FLUKA ISAJET Ali. Root Virtual MC Ali. Reconstruction HIJING Ali. Simulation EVGEN Ali. En HBTAN STEER MEVSIM PYTHIA 6 PDF PMD STRUCT EMCAL CRT TRD ITS START PHOS FMD ESD TOF MUON ZDC TPC RICH HBTP RALICE NEW Ali. Analysis 19/03/2004 ROOT P. Hristov 5

Current Status ■ ■ Major changes in the last year ■ New multi-file I/O finally in full production ■ New coordinate system ■ New reconstruction and simulations classes ■ First attempt at the ESD and analysis framework ■ Improvements in reconstruction and simulation Clearly the system works well, however a lot of changes to come ■ ESD: the philosophy is still evolving ■ Introduction of FLUKA and new geometrical modeller ■ Development of the analysis framework ■ Raw data for all the detectors -- we need them for the data challenge ■ Introduction of the condition database infrastructure 19/03/2004 P. Hristov 6

PDC’ 04 Schema Ali. En job control Production of RAW Shipment of RAW to CERN Reconstruction of RAW in all T 1’s Analysis Tier 2 19/03/2004 Tier 1 P. Hristov Data transfer CERN Tier 1 Tier 2 7

Merging Signal-free event 19/03/2004 Merged signal P. Hristov 8

Ali. En, Genius & EDG/LCG User submits jobs Server Alien CEs/SEs LCG UI LCG RB LCG PFN Catalog LCG CEs/SEs Catalog LCG LFN 19/03/2004 LCG LFN = Ali. En PFN P. Hristov 9

ALICE PDC 04 & LCG ■ ■ All the production is started via Ali. En, the analysis will be done via Root/Proof/Ali. En LCG-2 is one CE element of Ali. En, which integrates seamlessly LCG and non LCG resources ■ ■ If LCG-2 works well, it gets a large amount of jobs, and it is used heavily If LCG-2 does not work well, Ali. En will privilege other resources, and it will be less used In all cases we will use LCG-2 as much as possible We will not need to take any decision: the performance of the system will decide for us 19/03/2004 P. Hristov 10

Short History ■ Jan 03: Requirements for ALICE PDC 04 presented to PEB ■ End Dec 03: Announcement of LCG-2 by mid February 2004 ■ Beg Jan 04: Decision to delay PDC 04 by one month waiting for LCG-2 ■ Beg Jan 04: LCG announces that there will be no SE in LCG-2 ■ Beg Feb 04: The WAN resources allocated by LCG for data storage are insufficient/inadequate ■ Mid Feb 04: Development of an ALICE solution, developed in haste and working against all odds! ■ End Feb 04: IT has also come up with a solution responding to a CMS requirement ■ End Feb 04: Production started, new sites being added ■ End Feb 04: Tape vault flooded -- our tapes have been spared ■ Beg Mar 04: castor nameserver has to be reinstalled (running on Linux 6. 2) ■ Beg Mar 04: castor servers have to be reinstalled for security ■ Beg Mar 04: LCG RB works differently on the different centres. ■ e. g. CNAF has to be switched on and off by hand, otherwise it “swallows” all the jobs! ■ Beg Mar 04: we are obtaining now close to 10 TB ■ Mid Mar 04: Files on the IT-provided pool are erased before being copied on tape 19/03/2004 P. Hristov 11

Data Challenge Statistics Picture from yesterday, 18/03/2004 19/03/2004 P. Hristov 12

Data Challenge Statistics 19/03/2004 P. Hristov 13

Data Challenge Statistics 19/03/2004 P. Hristov 14

Considerations ■ LCG is providing a lot of cycles ■ ■ Relations with LCG are in general good ■ ■ ■ ALICE is the first to use the system for production This required continuous efforts and interventions (ALICE and LCG), particularly due to lousy workload scheduling and lack of stability The lack of an SE will make reconstruction and analysis possible only under Ali. En They are sincerely willing to help But the system was not fully prepared for our PDC’ 04 LCG PR / planning can be improved! 19/03/2004 P. Hristov 15

Considerations (cont) ■ Next time we will start six months before! ■ ■ ■ The period Jan-Feb was well spent ■ ■ LCG needs to be “prompted” for resources and support Some ALICE people did not get well the philosophy of a DC Changes in Ali. Root improved performance and results Ali. En now has a more advanced SE solution The Offline members reacted extremely well to pressure and the exercise is definitely very useful We will reach the objectives! 19/03/2004 P. Hristov 16

ALICE Physics Data Challenges Period (milestone) Fraction of the final capacity (%) 06/01 -12/01 1% pp studies, reconstruction of TPC and ITS 5% • First test of the complete chain from simulation to reconstruction for the PPR • Simple analysis tools • Digits in ROOT format 10% • Complete chain used for trigger studies • Prototype of the analysis tools • Comparison with parameterised Monte. Carlo • Simulated raw data 05/05 -07/05 TBD • Refinement of jet studies • Test of new infrastructure and MW • TBD 01/06 -06/06 20% • Test of the final system for reconstruction and analysis 06/02 -12/02 01/04 -06/04 NEW 19/03/2004 Physics Objective P. Hristov NEW 17