CERN as Tier-0

Tier-0 is a duty, not a privilege: safe-keeping of the raw data’s first copy, first-pass reconstruction, distribution to the Tier-1s and reprocessing during LHC down-times. It is the commitment that justifies the capital expenditure — the prevessin-computing-centre exists to meet it.

---

Topology

• Part of: tier-model
• Complies with: wlcg-mou-agreement
• Backed by: eos — the first copy of the raw data lands on disk.
• Backed by: cta — and its custodial copy on tape.
• Reached via: lhcopn — how it distributes to the Tier-1s.
• Cites: wlcg-tiers — Tier-0 responsibilities.
• Cites: mtp-2025-2029 — the Tier-0 obligation as budget justification.