Transcript Association of jet with signal vertex

Physicists's experience of the EGEE/LCG
infrastructure usage for CMS jobs submission
Natalia Ilina (ITEP Moscow)
NEC’2007
Outline
What do physicists need to know about grid?
Overview of existing frameworks for jobs submission in CMS
Specific of grid tutorials for physicists
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What do physicists need to know about grid?
1.
Bench mark – terminology: UI, CE, SE, WN, RB, VO…
UI (User Interface) – a machine where user’s certificate is installed. From
the UI user can be authenticated to use the Grid resources, submit a
job for execution on a CE, list all the resources suitable to execute a
job, replicate and copy files, cancel jobs, retrieve the output, show the
status of submitted jobs
CE (Computing Element) – a Grid batch queue, identified by a pair
<hostname>:<port>/<batch queue name>
SE (Storage Element) - provides uniform access and services to large
storage spaces. The SE may control large disk arrays, mass storage
systems (MSS) and the like.
2. Operations with user certificate
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3. The full chain for job submission with grid:
to find information about needed data
to write configuration file with the task
to organize the most useful saving of the output
maybe to realize the “bad” CE to save time
submit jobs
check the status
kill and resubmit jobs (if it’s necessary)
see and analyze the output
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DBS data discovery page for CMS
(very useful!)
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CMS frameworks for jobs submission: ASAP and CRAB
(from physicists point of view)
The aim - to simplify the work of users to create and to submit analysis
jobs into the grid environment.
Its purpose is to allow users, without specific knowledge of grid
infrastructure, to access and analyze remote data as easily as in a local
environment, hiding the complexity of distributed computational services.
Available tools:
ASAP (Arda Support for CMS Analysis Processing) :
https://lxarda13.cern.ch/docs/index.html
CRAB (CMS Remote Analysis Builder) - more popular among CMS physicists:
https://twiki.cern.ch/twiki/bin/view/Main/CRAB
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Example of configuration file for ASAP
# specify directory to store tasks
jobdir = /afs/cern.ch/user/n/nilina/ASAP
# store output at SE
store_output = 1
output_se = srm.cern.ch
output_se_path=/castor/cern.ch/user/n/nilina
# specify grid to submit to (lcg, my)
grid = lcg
#specify dataset
dbs_version = 2
primary_dataset = DY_mumu_10
tier = GEN-SIM-DIGI-RECO
processed_dataset = CMSSW_1_3_1-Spring07-1349
# pset file (CMSSW configuration file)
pset_file = Z2muons.cfg
output_files = MUONS.dat
events_required = 5000
events_per_job = 1000
# specify minimum time requirements for the job
min_wall_clock_time = 100
min_cpu_time = 100
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Example of configuration file for CRAB
[CRAB]
jobtype = cmssw
scheduler = glitecoll
[CMSSW]
datasetpath = /DY_mumu_10/CMSSW_1_3_1-Spring07-1349/GEN-SIM-DIGI-RECO
pset = test.cfg
total_number_of_events = 20000
events_per_job = 1000
output_file = MUONS.dat
use_dbs_2 = 1
[USER]
copy_data = 1
storage_element = srm.cern.ch
storage_path = /castor/cern.ch/user/n/nilina/Z2tau
return_data = 1
use_central_bossDB = 0
use_boss_rt = 0
[EDG]
rb = CERN
proxy_server = myproxy.cern.ch
virtual_organization = cms
retry_count = 0
lcg_catalog_type = lfc
lfc_host = lfc-cms-test.cern.ch
lfc_home = /grid/cms
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CRAB: already ready configuration files
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ASAP_Monitor - very nice feature
User can delegate responsibility for tasks to ASAP server. The server can process
and monitor the users jobs and perform resubmissions in the case of failure.
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Grid tutorials for physicists. Our experience.
We have already first experience – training courses in Russia (JINR, ITEP)
Lecture's part:
Program of the tutorial in ITEP (April 2007):
1. "Short introduction to LCG/EGEE"
2. "CMS user jobs submission with the usage of ASAP"
Practical part:
“CMS user jobs submission with the usage of ASAP”
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Specific of grid tutorials for physicists

Physicists don’t need to know all details about LCG infrastructure (only
main points)

Physicists need to get the results (output files) in the easiest way and
short time.

All practical steps of jobs submission should be clarified for participants
(from data finding to results retrieving)

Tutorial should have practical part – to provide the participants with first
experience (so participants should have already their grid certificates in
advance!)
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Summary
• LHC start-up is in the near future. So physicists should
be able to do the analysis with Grid
• Physicists don’t need to understand the details of LCG
infrastructure (in comparison with developers), but the
full chain of jobs submission should be clarified
•There are tools in CMS (CRAB, ASAP) which hide the
complexity from users
• The corresponding tutorials for physicists is needed
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