Disk storage at CERN

14 Apr 2015, 17:45
C209 (C209)



oral presentation Track3: Data store and access Track 3 Session


Luca Mascetti (CERN)


CERN IT DSS operates the main storage resources for data taking and physics analysis mainly via three system: AFS, CASTOR and EOS. The total usable space available for users is about 100 PB (with relative ratios 1:20:120). EOS deploys disk resources across the two CERN computer centres (Meyrin and Wigner) with a current ratio 60% to 40%. IT DSS is also providing sizable on-demand resources for general IT services most notably OpenStack and NFS clients. This is provided by our Ceph infrastructure and a few of proprietary servers (NetApp) for a total capacity of ~1 PB. We will describe our operational experience and recent changes to these systems with special emphasis to the following items: - Present usages for LHC data taking (new roles of CASTOR and EOS) - Convergence to commodity hardware (nodes with 200-TB each with optional SSD) shared across all services - Detailed study of the failure modes in the different services and approaches (RAID, RAIN, ZFS vs XFS, etc...) - Disaster recovery strategies (across the two CERN computer centres) - Experience in coupling commodity and home-grown solution (e.g. Ceph disk pools for AFS, CASTOR and NFS) - Future evolution of these systems in the WLCG realm and beyond

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