1. Workshop Computing Models status and perspectives
Bologna, 19 Febbraio 2015
ALICE CM:
status and perspectives
Domenico Elia
Domenico Elia
Workshop Computing Models / Bologna

2. Workshop Computing Models / Bologna 19.2.2015
Outline
Focus on Run2:
physics programme and rates, detector upgrades
basics for operations
software and process improvements
infrastructure improvements
resource considerations and requirements
Run3:
deep change in the CM expected
project being designed, Computing Upgrade TDR in progress
Domenico Elia
Workshop Computing Models / Bologna

3. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Physics programme, upgrades
Targeting integrated luminosity 1 nb-1 for PbPb:
by combination of Run1 and Run2 statistics
consistent with the ALICE approved programme
4-fold increase in instant luminosity for PbPb
Domenico Elia
Workshop Computing Models / Bologna

4. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Physics programme, upgrades
Targeting integrated luminosity 1 nb-1 for PbPb:
by combination of Run1 and Run2 statistics
consistent with the ALICE approved programme
4-fold increase in instant luminosity for PbPb
Double event rate of TPC/TRD:
consolidation of TPC and TRD readout electronics
Increased capacity of HLT and DAQ:
rate up to 8 GB/sec to T0 (for Heavy-Ion data taking)
Domenico Elia
Workshop Computing Models / Bologna

5. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Physics programme, upgrades
Detector upgrades:
TRD (+5 modules), full azimuthal coverage
PHOS (+1 module)
DCAL (new calorimeter)
+5 TRD’s
+1 PHOS
DCAL
Domenico Elia
Workshop Computing Models / Bologna

6. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Basics of Run2 operations
ALICE Grid model largely unchanged in Run2:
integration of every new computing centre
average 2 replicas of analysis objects:
dependency on resource stability, 1 copy for least popular data
Domenico Elia
Workshop Computing Models / Bologna

7. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Basics of Run2 operations
ALICE Grid model largely unchanged in Run2:
integration of every new computing centre
average 2 replicas of analysis objects:
dependency on resource stability, 1 copy for least popular data
low differentiation of tasks:
T0/T1 still raw data keepers/producers
all other tasks (MC + analysis) performed everywhere
tasks generally sent to data, but data can go to tasks if needed:
jobs go to data, in case of failure read from closest replica (<5%)
ALICE global data distribution by exclusive use of xrootd protocol
Domenico Elia
Workshop Computing Models / Bologna

8. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Basics of Run2 operations
ALICE Grid model largely unchanged in Run2:
integration of every new computing centre
average 2 replicas of analysis objects:
dependency on resource stability, 1 copy for least popular data
low differentiation of tasks:
T0/T1 still raw data keepers/producers
all other tasks (MC + analysis) performed everywhere
tasks generally sent to data, but data can go to tasks if needed:
jobs go to data, in case of failure read from closest replica (<5%)
ALICE global data distribution by exclusive use of xrootd protocol
analysis input mostly on AODs (limited use of ESDs)
push analyzers to organized trains (LEGO framework)
Domenico Elia
Workshop Computing Models / Bologna

9. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Basics of Run2 operations
Computing tasks and workflow:
Domenico Elia
Workshop Computing Models / Bologna

10. Efficiency per workflow
ALICE CM: Focus on Run2
Wall time resource share 2014
RAW data processing: 3%
@ T0/T1s only
Individual analysis: 14%
@all centres
425 users
Organized analysis: 14%
@all centres
Efficiency per workflow
(average over all sites)
MC productions: 69%
@all centres
Domenico Elia
Workshop Computing Models / Bologna

11. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Software and process impro’s
Evolution of the CM:
new version of the software framework (AliRoot 5.x)
use of HLT for online Raw data compression (factor 4):
already tested in Run1, implies reduction of tape Tier-0/1
use of HLT for calibration:
move first calibration iteration to online
Domenico Elia
Workshop Computing Models / Bologna

12. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Software and process impro’s
Evolution of the CM:
new version of the software framework (AliRoot 5.x)
use of HLT for online Raw data compression (factor 4):
already tested in Run1, implies reduction of tape Tier-0/1
use of HLT for calibration:
move first calibration iteration to online
use of HLT track seeds for offline reconstruction
improve performance of GEANT4 simulation for ALICE
further development of fast and parametrized simulation
Domenico Elia
Workshop Computing Models / Bologna

13. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Software and process impro’s
Evolution of the CM
Additional software and process improvements:
start adapting ALICE distributed computing to Cloud, using of
HLT farm for offline processing
corresponds to additional 3% CPU resources
improving performance of the organized analysis trains
speeding up and improving the efficiency of the analysis activity
by active data management
explore contributed resources:
ie spare CPU cycles on supercomputers
collaborating with other experiment on this issue
Domenico Elia
Workshop Computing Models / Bologna

14. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Infrastructure improvements
Focus on SE stability:
major factor for successful analysis and high CPU efficiency
goal for all SEs: > 98% availability
Domenico Elia
Workshop Computing Models / Bologna

15. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Infrastructure improvements
Focus on SE stability
LHCone programme:
brings substantial improvement in inter-site connectivity
allows for further diluition of boundaries between sites and tasks
Europe largely covered, focus on South America and Asia
Network use will increase:
large data volumes, more to transfer between sites
remote access to storage
Domenico Elia
Workshop Computing Models / Bologna

16. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Infrastructure improvements
Focus on SE stability
LHCone programme
Network use will increase
IPv6 adoption:
IPv4 address depletion is already a fact for new sites
ALICE services are IPv6 ready
xrootd v.4 should be IPv6 ready (release end of May)
other sevices are being brought into compliance
Domenico Elia
Workshop Computing Models / Bologna

17. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Infrastructure improvements
Focus on SE stability
LHCone programme
Network use will increase
IPv6 adoption
Refurbishment of SAM/SUM tests:
WLCG monitoring consolidation projet, advanced status
Site tests will reflect more and more the VO tests:
in the ALICE case provided by MonALISA
Domenico Elia
Workshop Computing Models / Bologna

18. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Resource considerations
Basic assumptions for Run2 resource estimate:
same CPU power needed for reconstruction
25% larger raw event size:
additional detectors, detector coverage
higher track multiplicity with increased beam energy and pileup
MC productions: 100% pp, pPb % PbPb events
Domenico Elia
Workshop Computing Models / Bologna

19. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Resource considerations
Basic assumptions for Run2 resource estimate:
same CPU power needed for reconstruction
25% larger raw event size:
additional detectors, detector coverage
higher track multiplicity with increased beam energy and pileup
MC productions: 100% pp, pPb % PbPb events
Resource requirements for 2015:
scrutinized and approved by CRSG in April 2014
CPU request growth compatible with “flat budget”
tape and disk resources increase after 2013/14 flat profile
major demand on resources towards end of 2015 (PbPb run)
Domenico Elia
Workshop Computing Models / Bologna

20. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Resource considerations
Resource requirements :
Domenico Elia
Workshop Computing Models / Bologna

21. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Resource considerations
Resource requirements :
T1+T2 resource increase
compared to previous year:
2015: 7%
2016: 25%
2017: 20%
Domenico Elia
Workshop Computing Models / Bologna

22. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Resource considerations
Resource requirements :
T1+T2 resource increase
compared to previous year:
2015: 66%
2016: 17%
2017: 17%
Domenico Elia
Workshop Computing Models / Bologna

23. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Resource considerations
Resource requirements :
T1 resource increase
compared to previous year:
2015: 57%
2016: 52%
2017: 26%
Domenico Elia
Workshop Computing Models / Bologna

24. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
Detectors and running scenario:
ALICE upgrade aiming to high statistics sample (10 nb-1)
continuous readout TPC, upgraded ITS
50 kHz PbPb interaction rate (current rate x100)
~1.1 TB /s detector readout
Domenico Elia
Workshop Computing Models / Bologna

25. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
Detectors and running scenario
Reconstruction strategy:
data reduction by (partial) online reconstruction and compression
Store only reconstruction results, discard raw data
demonstrated with TPC cluster finder running on HLT since PbPb 2011
using data structures optimized for lossless compression
using algorithms designed to allow for subsequent offline
reconstruction passes with improved calibrations
implies much tighter coupling between Online and Offline
reconstruction software  O2 Project
Domenico Elia
Workshop Computing Models / Bologna

26. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
Detectors and running scenario
Reconstruction strategy:
data reduction by (partial) online reconstruction and compression
Store only reconstruction results, discard raw data
- demonstrated with TPC cluster finder running on HLT since PbPb 2011
- using data structures optimized for lossless compression
- using algorithms designed to allow for subsequent offline
reconstuction passes with improved calibrations
From Detector Readout to Analysis, from DAQ, HLT to Offline: together, one computing framework  O2 project
Domenico Elia
Workshop Computing Models / Bologna

27. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
Detectors and running scenario
Reconstruction strategy
Simulation strategy:
migrate from G3 to G4
expect to profit from future G4 developments
multithreaded G4, G4 on GPU …
be ready to use contributed resources
supercomputers, volunteer computing resources
must work on (fast) parametrized simulation
basic support exists in the current framework
must make more use of embedding, event mixing
Domenico Elia
Workshop Computing Models / Bologna

28. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
Detectors and running scenario
Reconstruction strategy
Simulation strategy
O2 project and basics of the new CM:
project started on March 2013
Tier-0 (online, using FPGA, GPU, MCCPU etc)
MC and Tier-1/2’s (AF on Demand)
evolution of the framework AliRoot 5.x  6.x
working on AliRoot 6.x already started in collaboration with FAIR
Domenico Elia
Workshop Computing Models / Bologna

29. Perspectives for Run3 Software development timeline (Predrag Buncic)
ALICE CM: Run3
Perspectives for Run3
Evolution of current framework
Root 5.x
Improve the algorithms and procedures
Software development timeline
(Predrag Buncic)
AliRoot 5.x
New modern framework
Root 6.x, C++11
Optimized for I/O
FPGA, GPU, MIC…
AliRoot 6.x
Run 1
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
LS1
Run 2
LS2
Run 3
2022
2023
LS3
Run 4
Domenico Elia
Workshop Computing Models / Bologna

30. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
Detectors and running scenario
Reconstruction strategy
Simulation strategy
O2 project and basics of the new CM:
project started on March 2013
Tier-0 (online, using FPGA, GPU, MCCPU etc)
MC and Tier-1/2’s (AF on Demand)
evolution of the framework AliRoot 5.x  6.x
adapting ALICE distributed computing to Cloud
Domenico Elia
Workshop Computing Models / Bologna

31. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
In order to reduce complexity national or regional T1/T2 centers could transform themselves into Cloud regions. Providing IaaS and reliable data services with very good network between the sites.
Domenico Elia
Workshop Computing Models / Bologna

32. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
Detectors and running scenario
Reconstruction strategy
Simulation strategy
O2 project and basics of the new CM
Computing Upgrade TDR to the LHCC meeting on June 2015
initially expected by October 2014
delay not due to changes in the strategy but:
enlarged scope (project to be presented in its global environment)
associate to TDR all institutes showing active interest
more simulation, benchmark and prototypoing results
Domenico Elia
Workshop Computing Models / Bologna

33. Workshop Computing Models / Bologna 19.2.2015
Summary
Run2:
data volume in the period expected ~3x Run1
focus of the Grid development will be on improving the analysis
efficiency and decreasing the turnaround time of organized trains
several other software and process improvements
site performance and stability will continue to be a key factor for
success of the ALICE offline computing
planned resource increase expected to meet the demands,
working on data popularity monitoring and replica limitation
Run3:
TDR in progress, going to be discussed with LHCC in June
Domenico Elia
Workshop Computing Models / Bologna

34. Workshop Computing Models / Bologna 19.2.2015
Backup slides
Domenico Elia
Workshop Computing Models / Bologna

35. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: status and perspectives
Integrated data from Run1
Data taking 2010:
0.9 – 7 TeV
TeV (MB)
2011:
– 7 TeV (MB & rare)
TeV (MB & rare) :
8 TeV (rare)
TeV (pilot, 2012)
TeV (MB & rare, 2013)
Total data volume:
7.3 PB raw data
2 CERN (T0) T1s
copies on T1s (“good” data only)
16 PB derived data
Domenico Elia
Workshop Computing Models / Bologna

36. Workshop Computing Models / Bologna 19.2.2015
Status of the ALICE computing
Grid running profile
Progressive reduction of User analysis with
increasing usage of “LEGO trains” in the last 2 years
Domenico Elia
Workshop Computing Models / Bologna

37. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Focus on Run2
Efficiency per workflow
Average over all sites
Domenico Elia
Workshop Computing Models / Bologna

38. Workshop Computing Models / Bologna 19.2.2015
Status of the ALICE computing
CPU efficiency
Improved a lot in the last few years:
Main actions:
modifications of the OCDB structure
improvement of raw processing
more efficient analysis trains (LEGO framework)
moving users from ESDs to AODs
several steps
from ~50-60% (2011)
to current average
(unweighted):
Tier-0/1: ~85%
Tier-2: ~80%
Domenico Elia
Workshop Computing Models / Bologna

39. Workshop Computing Models / Bologna 19.2.2015
Status of the ALICE computing
Computing sharing in 2013
ALICE total: 50/50 (T0+T1s)/T2s
~290M Wall hours (260M in 2012)
Italian contribution:
50/50 T1/T2s
~43M Wall hours (15% of the total)
Domenico Elia
Workshop Computing Models / Bologna

40. Workshop Computing Models / Bologna 19.2.2015
Status of the ALICE computing
Italian Tier-1
L. Morganti, S. Taneja, CdG Tier
TAPE (TB)
DISK (TB)
Low consumption of tape storage compared to requirements
due to revised strategy of data preservation:
ALICE analysis not using data on tape due to high latency of the tape system
(ESDs and AODs data reside on disk)
obsolete data permanently deleted and not saved to tape
 new requirements reflect this practice
Domenico Elia
Workshop Computing Models / Bologna

41. Workshop Computing Models / Bologna 19.2.2015
Status of the ALICE computing
Italian Tier-2’s
Site Availability from EGI monthly reports (Jan 2013 – Mar 2014):
Italian Tier-2’s quite satisfactory, all above the average
CNAF 99.0%
Average 90.8%
BA 95.1%
CT 92.7% PD-LNL 98.8%
TO 91.2%
Domenico Elia
Workshop Computing Models / Bologna

42. Workshop Computing Models / Bologna 19.2.2015
ALICE CM: Run3
Perspectives for Run3
Domenico Elia
Workshop Computing Models / Bologna