Tier III

An Uptime classification meaning concurrently maintainable: any component can be serviced without taking IT load down.

Current numbers

Tier IV ~26 min/yrdowntime the commissioning agent's IST exists to prove (vs Tier III ~1.6 hr/yr)as of 2025 · register ↗

99.982% / 99.995%legacy Tier III / Tier IV availability (~1.6 hr vs ~26 min/yr down) — figures Uptime no longer endorsesas of 2025 · register ↗

~25–40% facilitycapital premium for Tier IV (fault-tolerant) over Tier III (concurrently maintainable)as of 2024-05 · register ↗