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CMU Tier ThreeΒΆ

The CMU group operates a Tier 3 in the LHC Computing Grid. It is primarily used for storage, of which it has about 250 TB, and not for processing. If you would like a home directory set up for you, talk to or email Andrew Roberts (email). The Tier 3's IP is cmsdata.phys.cmu.edu. In addition to a home directory, each user owns a folder in /store/user/ that can be accessed from other sites, for example from LXPlus and LPC.

In general, you will need to initialize your grid certificate before you will be able to read or write, using for example voms-proxy-init -voms cms. You can read and write to the Tier 3 in a variety of ways:

  • Crab

    • You can write to CMSData with Crab by using the following lines in your crab config python file:
      • config.Site.storageSite = 'T3_US_CMU'
      • config.Data.outLFNDirBase = '/store/user/[your username]/path/to/directory'
    • Tested on LPC

  • XRootD

    • Read:
      • xrdcp root://cmsdata.phys.cmu.edu//store/user/[your username]/path/to/filename path/to/new_filename
    • Write:
      • xrdcp path/to/filename root://cmsdata.phys.cmu.edu//store/user/[your username]/path/to/new_filename
    • Other filesystem commands can be performed using xrdfs:
      • Make a directory xrdfs root://cmsdata.phys.cmu.edu/ mkdir /store/user/[your username]/path/to/new_directory
      • More details are at xrdfs documentation
      • In general, this is the correct way to interact with the /store/ filesystem
    • Tested on LPC, LXPlus

  • Davix

    • Read:
      • davix-get davs://cmsdata.phys.cmu.edu:1094/store/user/[your username]/path/to/filename -P grid
    • Write:
      • davix-put path/to/filename davs://cmsdata.phys.cmu.edu:1094//store/user/acrobert/path/to/new_filename -P grid
    • The prefix https:// for the URL can be used instead of davs://
    • Tested on LXPlus (not available on LPC)

  • Macaroons

    • Macaroons is a token system which allows you to read and write using a token while the token is valid without additional authentication
    • Generate macaroon, which can do operations listed and is valid for in this case 30 minutes (maximum validity is one day):
      • Need to have initialized grid certificate with proxy located at /tmp/[your cert loc].
      • curl -L --capath /etc/grid-security/certificates/ --cacert /tmp/[your cert loc] -E /tmp/[your cert loc] -X POST -H Content-Type:application/macaroon-request -d "{\"caveats\":[\"activity:UPLOAD,DOWNLOAD,LIST,READ_METADATA\"], \"validity\": \"PT30M\"}" https://cmsdata.phys.cmu.edu:1094/store/user/[your username]
    • This will throw an ugly string at you, which is the macaroon
    • Read:
      • curl -v -H "Authorization: Bearer [macaroon]" https://cmsdata.phys.cmu.edu:1094/store/user/[your username]/path/to/file
    • Write:
      • curl -T path/to/file https://cmsdata.phys.cmu.edu:1094/store/user/[your username]/path/to/file -H "Authorization: Bearer [macaroon]"
    • Tested on LXPlus

  • GridFTP is no longer supported on the Tier 3