Analyzing Millions of Gigabyte of LHC Data for CMS - Discover the Higgs on OSG

Introduction

• Demo is showing analysis workflow: discover the Higgs on OSG
  • Analysis code was prepared in the CMSSW framework:
    • EDAnalyzer accessing reconstructed tracks and writing out ROOT file with histograms:
      • transverse momentum of reconstructed tracks: p_T [GeV]
      • di-track invariant mass: m_mu,mu [GeV]
      • invariant mass of two di-track-objects: m_Z,Z [GeV]
  • Dataset discovery: use DBS/DLS discovery page to check availability and location of datasample: Higgs->ZZ->4mu
  • Analysis job execution on the GRID using CRAB

• Used components of the CMS software and computing environment
  • CMSSW: CMS software framework and EDM
  • DBS/DLS discovery webpage:
    • DBS: Dataset Bookkeeping System, database of datasets and their files
    • DLS: Dataset Location Service, database of location(s) of datasets (which dataset is available at which site)
  • CRAB: CMS Remote Analysis Builder, user tool to submit and control batch analysis jobs to the GRID

• CMSSW:
  • Based on a bus model, user schedules modules which are run by the main framework application: cmsRun
  • User interaction with the framework application is done through configuration file called parameter-set
  • Parameter-set instantiates modules, instance is labeled by the module label
  • 4 different types of modules, two main user modules:
    • EDProducer: uses input from the event and produces new output which is stored in the event
    • EDAnalyzer: uses input form the event and performs operations on input, does not store anything in the event (preparation shown in this demo)

• Locations:
  • User interface (UI): interactive login nodes at Fermilab (UAF)
  • GRID sites: one of the seven US-CMS T2 sites
    • University of Nebraska, Lincoln (UNL, OSG middleware)
    • University of Wisconsin, Madison (Wisconsin, OSG middleware)
    • California Institute of Technology (Caltech, OSG middleware)
    • Massachusetts Institute of Technology (MIT, OSG middleware)
    • Purdue University (Purdue, OSG middleware)

• Format conventions

Setup environment and prepare user area

• Setup CMS software environment

Analysis code preparation

• Code preparation

Dataset discovery

• Data discovery on DBS/DLS discovery page http://cmsdbs.cern.ch/discovery/
  • keyword search for:
    • Higgs-ZZ-4mu

Analysis job execution on OSG

• Setup CRAB
• prepare CRAB configuration file

[CRAB]
jobtype                = cmssw
scheduler              = condor_g

[CMSSW]
datasetpath            = <dataset name discovered with discovery page
pset                       = <parameter-set for analysis code>
total_number_of_events = 100
events_per_job         = 10
output_file            = <histogram file name>

[EDG]
se_white_list          = <destination site>
virtual_organization   = cms
lcg_catalog_type       = lfc
lfc_host               = lfc-cms-test.cern.ch
lfc_home               = /grid/cms

• create jobs

crab -create

• submit jobs

crab -submit all -continue

• status check

crab -status -c

• output retrieval

crab -getoutput -c

Finalize analysis: histograms

• post processing: add histogram files of individual jobs using ROOT tool

cd crab_?_*_*/res
hadd histograms.root *.root

• Show histograms

root histograms.root
pt->Draw();
mmumu->Draw();
mzz->Draw();

Monitoring

• DashBoard