A Disk-based Archival Storage System Using the EOS Erasure Coding Implementation for the ALICE Experiment at the CERN LHC

  • Ahn, Sang Un (Korea Institute of Science and Technology Information (KISTI), Global Science experimental Data hub Center (GSDC)) ;
  • Betev, Latchezar (European Organization for Nuclear Research (CERN)) ;
  • Bonfillou, Eric (European Organization for Nuclear Research (CERN)) ;
  • Han, Heejune (Korea Institute of Science and Technology Information (KISTI)) ;
  • Kim, Jeongheon (Korea Institute of Science and Technology Information (KISTI)) ;
  • Lee, Seung Hee (Korea Institute of Science and Technology Information (KISTI)) ;
  • Panzer-Steindel, Bernd (European Organization for Nuclear Research (CERN)) ;
  • Peters, Andreas-Joachim (European Organization for Nuclear Research (CERN)) ;
  • Yoon, Heejun (Korea Institute of Science and Technology Information (KISTI))
  • Received : 2022.04.21
  • Accepted : 2022.06.20
  • Published : 2022.06.20


Korea Institute of Science and Technology Information (KISTI) is a Worldwide LHC Computing Grid (WLCG) Tier-1 center mandated to preserve raw data produced from A Large Ion Collider Experiment (ALICE) experiment using the world's largest particle accelerator, the Large Hadron Collider (LHC) at European Organization for Nuclear Research (CERN). Physical medium used widely for long-term data preservation is tape, thanks to its reliability and least price per capacity compared to other media such as optical disk, hard disk, and solid-state disk. However, decreasing numbers of manufacturers for both tape drives and cartridges, and patent disputes among them escalated risk of market. As alternative to tape-based data preservation strategy, we proposed disk-only erasure-coded archival storage system, Custodial Disk Storage (CDS), powered by Exascale Open Storage (EOS), an open-source storage management software developed by CERN. CDS system consists of 18 high density Just-Bunch-Of-Disks (JBOD) enclosures attached to 9 servers through 12 Gbps Serial Attached SCSI (SAS) Host Bus Adapter (HBA) interfaces via multiple paths for redundancy and multiplexing. For data protection, we introduced Reed-Solomon (RS) (16, 4) Erasure Coding (EC) layout, where the number of data and parity blocks are 12 and 4 respectively, which gives the annual data loss probability equivalent to 5×10-14. In this paper, we discuss CDS system design based on JBOD products, performance limitations, and data protection strategy accommodating EOS EC implementation. We present CDS operations for ALICE experiment and long-term power consumption measurement.



This work was supported by the National Research Foundation of Korea (NRF) through contract N-22-NM-CR02 and the Program of Data Computing Service for Large-scale Experimental Data (K-22-L02-C02).


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