The Central Data Recording (CDR) system is a software tool for the transfer of raw physics data from online data acquisition systems (DAQs) to permanent offline storage. The aim of the CDR service is to provide a reliable and resilient system for fast and efficient storage of raw data, whilst ensuring data integrity at all times.

The CDR system makes use of the CERN network infrastructure to provide a direct link to the computer centre to transfer data to a mass storage system (MSS) called CASTOR, a CERN developed MSS system that is seen as the candidate solution for LHC data storage. To this end, 4 dedicated public CDR servers running CASTOR were installed in 2001. This central service will be expanded in the future as needed.

The CDR service is operated by the CERN IT division, and responsibility currently lies with the FIO group. The service is available for use by all experiments at CERN, and runs continuously. 'Best effort' support is provided during data taking periods.