Speaker
Description
The CERN IT Storage Group ensures the symbiotic development
and operations of storage and data transfer services for all CERN physics data,
in particular the data generated by the four LHC experiments (ALICE, ATLAS,
CMS and LHCb).
In order to accomplish the objectives of the next run of the LHC (Run-3), the
Storage Group has undertaken a thorough analysis of the experiments’ requirements,
matching them to the appropriate storage and data transfer solutions, and
undergoing a rigorous programme of testing to identify and solve any issues before
the start of Run-3.
In this paper, we present the main challenges presented by each of the four LHC
experiments. We describe their workflows, in particular how they communicate
with and use the key components provided by the Storage Group: the EOS
disk storage system; its archival back-end, the CERN Tape Archive (CTA); and
the File Transfer Service (FTS). We also describe the validation and commissioning
tests that have been undertaken and challenges overcome: the ATLAS
stress tests to push their DAQ system to its limits; the CMS migration from
PhEDEx to Rucio, followed by large-scale tests between EOS and CTA with
the new FTS “archive monitoring” feature; the LHCb Tier-0 to Tier-1 staging
tests and XRootD Third Party Copy (TPC) validation; and the erasure coding
performance in ALICE.
