concurrent maintainability (any path serviceable, no load impact) vs fault tolerance (survive any single unplanned fault)
Tier III vs IVobserved
| Value kind | observed — Reported measurements, counts, and specifications keep the precision and scope stated by their source; an exact specification is not treated as a range. |
|---|---|
| As of | 2026-10 |
| Source | Uptime Institute Tier Standard · Tier III and Tier IV descriptions; Tier Standard: Topology for the normative criteria |
| Review | checking…review by 2027-10-16 · standard cadence |
| Recorded changes | last 2026-10-16 · 2 revisions tracked |
| Claim id | concurrent-maintainability-any-path-serviceable |
Where the guide uses it
← Full numbers register — every date-stamped figure in the guide, with revision history.