Tier 2 redundancy is contingent on continued coordination of 3-4 organizations

Tier 2 maintains multiple copies across multiple locations, coordinated by institutional agreements and funded through membership fees, research libraries, and philanthropic support. The most sophisticated coordinated preservation systems on Earth — INSDC (3 sites), wwPDB (4 sites), CLOCKSS (12 mirror nodes, 691 publishers), WLCG (>170 sites in 42 countries), NOAA NCEI (4 U.S. locations), and the IVOA partnership (3 sites across 30 years) — operate at this tier.

The architectural limitation is economic and organizational rather than technical. A Tier 2 network depends on the continued coordination of a small number of organizations, and that coordination requires continuous operational funding. When funding or coordination fails, the redundancy members paid for is no longer the redundancy they have. The MetaArchive 2025 sunset (E-0066) and the Digital Preservation Network 2018 dissolution (E-0065) are documented cases in which this dependency converted to actual preservation gaps.

The institutional copies are physically independent; the organizational, political, and budgetary domains governing them frequently are not. NOAA NCEI's four U.S. locations all report to the same agency — a single budget decision at one level of government can affect all four. The FY2026 ~27% NOAA cut and the proposed defunding of Mauna Loa's 68-year CO₂ record (S-0032) illustrate the failure mode.

Three or four independently-maintained copies is the demonstrated state of the art in coordinated scientific preservation. Tier 2 is not a failure mode within its scope; it is a successful architecture whose resilience is bounded by the continued coordination it requires.