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Based on the observations above we propose to:

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the following modifications:

  • Change the lifetime for raw and scratch data on disk to 4 months.
  • After the initial 4 months period, the expiration status of a run is determined by the access pattern of its files. 
    • This will be enforced by the constant monitoring of the file systems to determine which files were accessed and when. We will be also tracking if the files were actually analyzed or just "touched" to dodge the policy. 
    • Analyzing the data extends the lifetime of the accessed data by 1 month from the access date.
    • Data restored from tape will stay on disk for 1 month, i.e. it's treated as a file access.
  • Eliminate the short and medium storage classes.
  • Eliminate the /ftc folder.
    • Data currently under ftc will be moved to scratch and the scratch policy will apply.
  • Rename the usr folder as usrdaq.
  • Rename the res folder as results.
  • Increase the quota of the results folder to 2TB4TB.

Notes

  • Please do not store under the scratch folder data that you cannot recreate because this directory is not backed up and the oldest files on scratch may be deleted at any time to make space for data from new experiments.
  • The tape archive (xtc, hdf5, usrdaq) and the tape backup (results, home) are fundamentally different:
    • In the tape archive the folders are frozen after the end of the experiments and their contents are stored on tape once. 
    • In the tape backup, the system takes snapshots of the folders as appear at a given time. this implies that files which are deleted from disk are eventually, i.e. after a long enough time, also deleted from tape.
  • For raw data the cleanup operations will affect all files, i.e. all streams and chunks, which make up one run, rather than individual files.
  • After 10 years we plan to remove the archiver tapes from the silos and store them in a safe environment.
  • The new policy will apply to all experiments, i.e. it will be retroactive, and its deployment date will coincide with the start of Run 14 (August 10th 2016).

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