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ALICE Site Requirements#

This document describes ALICE-specific requirements for sites that envisage joining the ALICE grid infrastructure at Tier-3 or Tier-2 level, in particular without custodial storage responsibilities.

Each ALICE site needs to run an "edge service" called VO-Box, which stands for Virtual Organization Box, in this case dedicated to the ALICE VO, on which ALICE-specific services (provided via CVMFS) have these responsibilities:

  • job submission to the site's Computing Element(s) or batch system;
  • monitoring through MonALISA of:
    • jobs;
    • the site's Storage Element(s);
    • the site's network connectivity to other ALICE sites and to the ALICE central services at CERN.

The site maintains its VO-Box(es), while the ALICE-specific services run under an unprivileged account.

There also are requirements and recommendations for the selection and configuration of computing, storage and network services, which are further detailed below.

Services#

VO-Box#

Please consult these links:

Computing - job management#

  • Jobs can be submitted directly to the batch system, if desirable
    • Used at a few sites
  • Most sites require use of a Computing Element
    • HTCondor CE - used by most of the big sites
    • ARC CE - we do not use its data handling features
  • Batch systems
    • HTCondor - the most popular
    • Slurm
    • PBS/Torque - is becoming rare at our sites
  • Batch queue configuration
    • Allow a maximum job lifetime (TTL) of several days, if possible
    • Allow whole-node jobs, if possible
    • Else 16- or 8-core job slots
    • If a CE is used, allow 1-core job slots for availability tests

Computing - worker nodes#

  • OS: RHEL / AlmaLinux / Rocky Linux v9
    • Other Linux flavors might work, but would need to be discussed
  • 50 GB CVMFS cache
  • At the very least 2 GB RAM per core, preferably at least 3
  • 5 GB swap per core (can also be included in the RAM)
  • 10 GB job directory scratch space per core
  • LAN speed: 5 MB/s per core

Storage#

  • Preferably EOS or plain XRootD
    • Both can be fully integrated in MonALISA monitoring
  • 1 TB per core in the batch share for ALICE
  • LAN speed: 5 MB/s per core in the batch share for ALICE

External network#

  • Minimum speed 10 Gbps
  • Larger sites: 1 Mbps per core in the batch share for ALICE
  • Connection to LHCONE desirable