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HowTo use EOS from the PSI Tier-3

EOS requires a kerberos ticket or your grid proxy for authenticating. So, you have to either do a kinit using your CERN account name and password

$ kinit cern_username@CERN.CH

or you need to create a grid-proxy

voms-proxy-init -voms cms -voms cms:/cms/chcms

Available EOS endpoints

  • root://eoscms.cern.ch : the main CMS namespace where you e.g. find /eos/cms/store/mc and /eos/cms/store/user
  • root://eoshome-a.cern.ch, root://eoshome-b.cern.ch, ... : EOS home directory endpoints, one per username initial, where you can e.g. find root://eoshome-e.cern.ch//eos/user/e/exmpleuser

Define your endpoint in the EOS_MGM_URL environment variable or on the command line of the eos client commands. Here are some examples of eos subcommands (ls, cp). There are other subcommands, consult the eos man page.

Commands using the eos client:

export EOS_MGM_URL=root://eoscms.cern.ch

eos ls -l /eos/cms/store/test/loadtest/source/T2_CH_CSCS/urandom.270MB.file0001
-rw-r--r--   2 phedex   zh          270000000 Feb 20 12:06 urandom.270MB.file0001

eos cp /eos/cms/store/test/loadtest/source/T2_CH_CSCS/urandom.270MB.file0001 /scratch/feichtinger/test
[eoscp] urandom.270MB.file0001   Total 257.49 MB        |====================| 100.00 % [97.8 MB/s]
[eos-cp] copied 1/1 files and 270.00 MB in 3.52 seconds with 76.62 MB/s

You can also use normal xrootd URLs to interact with the files from the command line or in your programs. This requires a grid proxy certificate for authentication (no kerberos). E.g. to interact with files in the home of my account dfeich, I can use:

  xrdfs eoshome-d.cern.ch ls /eos/user/d/dfeich/testfile-df
  # is equivalent to this
  eos root://eoshome-d.cern.ch ls /eos/user/d/dfeich/testfile-df

  xrdcp root://eoshome-d.cern.ch//eos/user/d/dfeich/testfile-df /scratch/feichtinger/mytest