Grid Certificate and CMS VO registration

Both of grid certificate and CMS VO registration is needed for visiting DAS(Data Aggregation System).

Grid Certificate

Grid Certificate can be obtained in CERN Certification Authority. Then you need install the certificate on both your personal computer and remote host in CERN(lxplus.cern.ch).

For personal computer, just doule-click the certificate you downloaded and follow the instructions the installer shows.

For remote host, you should firstly upload your certificate to the host (e.g by FileZilla). Then

$ cd ~
$ mkdir .globus
$ cd ~/.globus
$ mv /path/to/mycert.p12 .
$ rm -f usercert.pem
$ rm -f userkey.pem
$ openssl pkcs12 -in mycert.p12 -clcerts -nokeys -out usercert.pem
$ openssl pkcs12 -in mycert.p12 -nocerts -out userkey.pem
$ chmod 400 userkey.pem
$ chmod 400 usercert.pem

CMS VO Registration

The registration can be done here.

Github

Github account is needed for checkint out and developing CMSSW.If you dont have a Github account you can get one here.

After you have a Github account, fork CMSSW.

You shoule generate a ssh key for the remote host by following instructions here.Then register your ssh key in your Github account.

In your terminal at lxplus.cern.ch, execute

$ git config --global user.name "Your name" 
$ git config --global user.email "Your email"
$ git config --global user.github "Your user name in Github"

CMS Configuration

Put

$ source /cvmfs/cms.cern.ch/cmsset_default.csh #or .sh for bash

in your file ~/.bash_profile.

Then

cd ~/nobackup
mkdir YOURWORKINGAREA
cd YOURWORKINGAREA
cmsrel CMSSW_9_3_2
cd CMSSW_9_3_2/src
cmsenv
git cms-init

DAS(Data Aggregation System)

You can find DAS here.

To use DAS in your terminal, you should firstly

$ voms-proxy-init --voms cms

Then you can use DAS like this

das_client.py --query="dataset=/DoubleMuon*/Run2017C-PromptReco-v3/MINIAOD" --format=plain

More about DAS can be found here.

EDM

After my testing, the LFN(logical file name)

root://eoscms.cern.ch//eos/cms/store/relval/CMSSW_9_3_0_pre5/RelValZMM_13/MINIAODSIM/93X_mc2017_realistic_v2-v1/00000/96FBB6F5-0E92-E711 -841B-0025905B85C0.root

returned by edmFileUtil command can NOT be used to dump event content by command

edmDumpEvent root://eoscms.cern.ch//eos/cms/store/relval/CMSSW_9_3_0_pre5/RelValZMM_13/MINIAODSIM/93X_mc2017_realistic_v2-v1/00000/96FBB6F5-0E92-E711
-841B-0025905B85C0.root

. The PFN(physical file name)

/store/relval/CMSSW_9_3_0_pre5/RelValZMM_13/MINIAODSIM/93X_mc2017_realistic_v2-v1/00000/96FBB6F5-0E92-E711-841B-0025905B85C0.root

can not be used, either.

To dump event content in /store/relval/CMSSW_9_3_0_pre5/RelValZMM_13/MINIAODSIM/93X_mc2017_realistic_v2-v1/00000/96FBB6F5-0E92-E711-841B-0025905B85C0.root, you should firstly go to DAS and search by the PFN. Then clicking “Download” shown below, and use the LFN shown below

MiniOAD

The main contents of the MiniAOD are:

High level physics objects (leptons, photons, jets, ETmiss), with detailed information in order to allow e.g. retuning of identification criteria, saved using PAT dataformats. Some preselection requirements are applied on the objects, and objects failing these requirements are either not stored or stored only with a more limited set of information.
Some high level corrections are applied: L1+L2+L3(+residual) corrections to jets, type1 corrections to ETmiss. The full list of particles reconstructed by the ParticleFlow, though only storing the most basic quantities for each object (4-vector, impact parameter, pdg id, some quality flags), and with reduced numerical precision; these are useful to recompute isolation, or to perform jet substructure studies.
For charged particles with pT > 0.9 GeV, more information about the associated track is saved, including the covariance matrix, so that they can be used for b-tagging purposes.
MC Truth information: a subset of the genParticles enough to describe the hard scattering process, jet flavour information, and final state leptons and photons; GenJets with pT > 8 GeV are also stored, and so are the other mc summary information (e.g event weight, LHE header, PDF, PU information).
In addition, all the stable genParticles with mc status code 1 are also saved, to allow reclustering of GenJets with different algorithms and substructure studies.
Trigger information: MiniAOD contains the trigger bits associated to all paths, and all the trigger objects that have contributed to firing at least one filter within the trigger. In addition, we store all objects reconstructed at L1 and the L1 global trigger summary, and the prescale values of all the triggers.