Access Data via XrootD

Using the XRootD service (AAA) it is possible to read data stored in e.g Tier-2 Sites, CERN, Fermilab or to write to such sites if you have write permissions to do so. Please, read Section 5.13  of the CMS Offline Workbook for full instructions on how to either copy files via xrdcp or to directly open files via AAA using in CMSSW and ROOT. 

Notice that in order to use this service from the CMS Connect login node you will need to:

  • Setup a release of the CMSSW framework.
  • Have and initialize a valid proxy certificate.

Here is one example on how to access a file (having the Logical Filename) via AAA:

On ROOT:

ROOT
TFile *f =TFile::Open("root://cmsxrootd.fnal.gov///store/mc/SAM/GenericTTbar/GEN-SIM-RECO/CMSSW_5_3_1_START53_V5-v1/0013/CE4D66EB-5AAE-E111-96D6-003048D37524.root");

Otherwise, you can use xrdcp to copy your file:

xrdcp root://cmsxrootd.fnal.gov///store/mc/SAM/GenericTTbar/GEN-SIM-RECO/CMSSW_5_3_1_START53_V5-v1/0013/CE4D66EB-5AAE-E111-96D6-003048D37524.root foo.root