The tier model
The architecture that makes the grid a federation rather than a data centre: Tier-0 keeps the first copy of the raw data, does first-pass reconstruction and distributes; fifteen Tier-1s hold proportional shares with round-the-clock support and do large-scale reprocessing; Tier-2s are where analysis and simulation happen. Across ~170 centres in 40+ countries: ~3 exabytes and about a million cores — of which CERN provides only around 20% of the compute. The number is the argument for federated governance.
Topology
- Part of: wlcg-governance
- Contains: cern-tier0
- Complies with: wlcg-mou-agreement — resource levels are pledged against it.
- Cites: wlcg-tiers — the layer responsibilities and the scale figures.