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ATLAS Distributed Computing perspectives for Run-2 Simone Campana CERN-IT/SDC o n behalf of ADC. The Challenges of Run2. LHC operation Trigger rate 1 kHz (~400) Pile-up up above 30 (~20) 25 ns bunch spacing (~50) Centre-of-mass energy x ~2 Different detector - PowerPoint PPT Presentation
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IT-SDC : Support for Distributed Computing
ATLAS Distributed Computing perspectives for
Run-2
Simone Campana CERN-IT/SDCon behalf of ADC
IT-SDC
The Challenges of Run2
LHC operation Trigger rate 1 kHz (~400) Pile-up up above 30 (~20) 25 ns bunch spacing (~50) Centre-of-mass energy x ~2
Different detector
Constraints of ‘flat budget’ Both for hardware and for operation and development Data from Run1
8 July [email protected] – WLCG Workshop 2
IT-SDC
Where to optimize?CPU Consumption
Disk usage at T1s & T2s
SimulationCPU
ReconstructionCPU, Memory
AnalysisCPU, Disk Space
8 July [email protected] – WLCG Workshop 3
IT-SDC
Simulation
Simulation is CPU intensive
Integrated Simulation Framework (ISF) Mixing of full GEANT & fast
simulation within an event
Baseline for MC production
More events per 12h job, larger output files, less transfers/merging, less I/O
Or shorter, more granular jobs for opportunistic resources 8 July [email protected] – WLCG Workshop 4
IT-SDC
Reconstruction
Reconstruction is memory eager And requires non negligible CPU
AthenaMP default from 2014 (Almost) all production run on
multicore Analysis on single core
Optimization in code and algorithms
8 July [email protected] – WLCG Workshop 5
IT-SDC
Analysis Model
Common analysis data format: xAOD replacement of AOD & group
ntuple of any kind Readable both by Athena & ROOT
Data reduction framework AthenaMP to produce group data
sample• Centrally via Prodsys
Based on train model• one input, N outputs• from PB to TB
8 July [email protected] – WLCG Workshop 6
ChaoticOrganized (trains)
Organized (reprocessing)
IT-SDC
Computing Model: data processing Optional extension of first pass
processing from T0 to T1s
More flexible usage of resources Reduce the different between T1s and
T2s in the model Loosen the job-to-data colocation
Still one/two full reprocessing from RAW / year, but multiple AOD2AOD reprocessings/year
Derivation Framework (train model) for analysis datasets
Some T2s are equivalent to T1s in term of disk storage & CPU power
Need More Flexibility
8 July [email protected] – WLCG Workshop 7
IT-SDC
Computing Model: Run-2 data placement
Dynamic data placement and reduction of secondary (cache) replicas will continue
More data will be stored on tape beside disk
Only popular primary (pinned) dataset will be kept on disk after some time
All datasets will have a lifetime (from both disk and tape)
Access to data on tape still “organized” and not “chaotic”
8 July [email protected] – WLCG Workshop 8
T0/T1 DATADISK
pinned
pinned
cache
T2 DATADISK
IT-SDC
Preparation for Run-2
Alessandro will now present the work being done in preparation for Run-2
We will have a 3 days Jamboree (Dec 3-5) at CERN focused on sites related aspectsPlaceholder agenda at
https://indico.cern.ch/event/276502/
8 July [email protected] – WLCG Workshop 9