This is just a short summary how to access the ALFA testbeam data on the grid.

This assumes you already have a grid certificate and are ATLAS-VO member.

At first enable DQ2

source /afs/cern.ch/atlas/offline/external/GRID/ddm/DQ2Clients/setup.sh

and initialize the proxy

voms-proxy-init -voms atlas

Now everything should be ready to use. It is possible to access the raw data and processed data. Let's start with the raw data:

  • List all ALFA datasets
dq2-ls 'alfa*'
      

  • List all raw ALFA files of the 2009 testbeam
dq2-ls -f alfa09_testbeam_cern.000001.alfa_data.RAW.o1 
      

  • List all raw Eudet files of the 2009 testbeam
dq2-ls -f alfa09_testbeam_cern.000001.eudet_data.RAW.o1 
      

  • Download the complete dataset
dq2-get alfa09_testbeam_cern.000001.alfa_data.RAW.o1 
      

  • Download FILENAME from dataset. Multiple files can be downloaded, separated by commas
dq2-get -f FILENAME alfa09_testbeam_cern.000001.alfa_data.RAW.o1
      

The processed data can be accessed as follows:

  • To list the files
dq2-ls -L DESY-HH_ALFA -f group.det-alfa.eudet4.NTUP.o2
      

  • The file names are like
group.det-alfa.eudet4.NTUP.o2.xxxx-track-histo.root
      

  • To download a file
dq2-get -f group.det-alfa.eudet4.NTUP.o2.xxxx-track-histo.root group.det-alfa.eudet4.NTUP.o2
      
Where xxxx is the EUDET run number.

  • To write files in GRID (it can require some patience)
    • apply for the role "production" for the VO /atlas/det-alfa
    • dq2 should be already installed in your PC
    • type the command "voms-proxy-init --voms atlas:/atlas/det-alfa/Role=production" and enter your GRID password
    • create a directory e.g. path/datadirectory
    • copy your data (e.g. dataname.ext) in path/datadirectory
    • choose a name for your dataset. This is actually pretty important, since the name must be unique and must satisfy certain conditions...ask IT. Let say for the moment that the name of the dataset is dataset.name.unique
    • rename your data dataname.ext as dataset.name.unique.dataname.ext.
    • copy the files in the GRID scratch area DESY-HH_SCRATCHDISK with the command "dq2-put -C -s path/datadirectory -L DESY-HH_SCRATCHDISK dataset.name.unique"
    • copy from DESY-HH_SCRATCHDISK to DESY-HH_ALFA with the command "dq2-register-subscription dataset.name.unique DESY-HH_ALFA"
    • freeze your dataset with command "dq2-freeze-dataset dataset.name.unique"

Once you froze your dataset you cannot add more files to it and I don't know if you can replace files. Please don't ask me why they did so complicated.....

Compiled from talks from Michele & Dennis

-- FelixPfeiffer - 16-Jul-2010

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