WP1: Data preservation

The goal of this work package is the definition of a policy for the long term future preservation of LHCb data (bit preservation).


  • WP1.T1: Definition of Run 1 legacy dataset; locations of all datasets and available copies.
  • WP1.T2: For each archival location, check migration and data integrity procedures in place at that site. Definition of recovery procedures in case of file loss/damage.
  • WP1.T3: Definition of tests to regularly check data access (this task is in common with WP2 – software preservation - and WP3 – validation framework)


  • WP1.D1: Webpage collecting all information about Run 1 legacy datasets (locations, recovery procedures,...)
  • WP1.D2: Tests for periodic validation of data access and analysis. Reference results in LHCbPR. (in common with WP2 and WP3)



LHCb data are stored on tape and disk at Tier0 and Tier1 sites.

Backup policy

  • Raw data: 2 copies on tape, one at T0 and one in a Tier1

  • Full.DST: 1 copy on tape, for the most recent reprocessing
  • DST/mDST
    • 4 copies on disk for the latest reprocessing N (3 on T0D1 storage at selected T1s + 1 at T0)
    • 2 copies on disk for the N-1 reprocessing
    • One copy on T1D0 either at T0 or at one T1

Recovery Mechanisms

  • Raw data: as there are two copies of raw data in distinct locations, known losses can be recovered; currently there are no systematic checks on tape integrity
  • Full.DST: known losses can be recovered re-running the reconstruction
  • DST/mDST
    • for live data there is a mechanism to recover a lost disk copy from other disk copies
    • for archived data there is no recovery mechanism in plase, but DST/mDST can be regenerated
To do: which data integrity checks are in place in the Tier1s where LHCb data are stored?

Official Productions of LHCb data

The list of the official productions of LHCb data can be found here.

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Topic revision: r4 - 2014-01-10 - SilviaAmerio
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