The Long Term Data Preservation (LTDP) project at INFN CNAF: CDF use case

Abstract

In the last years the problem of preservation of scientific data has become one of the most important topics inside international scientific communities. In particular the long term preservation of experimental data, raw and all related derived formats including calibration information, is one of the emerging requirements within the High Energy Physics (HEP) community for experiments that have already concluded the data taking phase. The DPHEP group (Data Preservation in HEP) coordinates the local teams within the whole collaboration and the different Tiers (computing centers). The INFN-CNAF Tier-1 is one of the reference sites for data storage and computing in the LHC community but it also offers resources to many other HEP and non-HEP collaborations. In particular the CDF experiment has used the INFN-CNAF Tier-1 resources for many years and after the end of data taking in 2011, it is now facing the challenge to both preserve the large amount of data produced during several years and to retain the ability to access and reuse the whole amount of it in the future. According to this task the CDF Italian collaboration, together with the INFN-CNAF computing center, has developed and is now implementing a long term future data preservation project in collaboration with Fermilab (FNAL) computing sector. The project comprises the copy of all CDF raw data and user level ntuples (about 4 PB) at the INFN-CNAF site and the setup of a framework which will allow to access and analyze the data in the long term future. A portion of the 4 PB of data (raw data and analysis-level ntuples) are currently being copied from FNAL to the INFN-CNAF tape library backend and a system to allow data access is being setup. In addition to this data access system, a data analysis framework is being developed in order to run the complete CDF analysis chain in the long term future, from raw data reprocessing to analysis-level ntuples production and analysis. In this contribution we first illustrate the difficulties and the technical solutions adopted to copy, store and maintain CDF data at the INFN-CNAF Tier-1 computing center. In addition we describe how we are exploiting virtualization techniques for the purpose of building the long term future analysis framework.