A cloud provider advertises that its data centre has concurrently maintainable power and cooling, meaning any single capacity component or distribution path element can be taken out of service for planned maintenance without disrupting the IT load. Which Uptime Institute tier does this description match?
- ATier I, because it provides basic site infrastructure with dedicated space for IT systems.
- BTier II, because redundant capacity components protect against a single component failure.
- CTier IV, because only full fault tolerance allows a component to be removed for maintenance.
- DTier III, because concurrent maintainability requires redundant components and multiple distribution paths. Correct
Why A is wrong: Tier I offers only non-redundant capacity components and a single distribution path, so any maintenance or component failure drops the load; it does not meet the concurrently maintainable standard described.
Why B is wrong: Tier II adds redundant capacity components but still relies on a single distribution path, so maintaining that path disrupts the IT load; concurrent maintainability requires more than redundant components alone.
Why C is wrong: Tier IV is fault tolerant and withstands an unplanned failure, which is stronger than what is described; concurrent maintainability alone is the Tier III standard, so Tier IV over-specifies the requirement.
Why D is correct: Tier III is defined by concurrent maintainability: redundant capacity components plus multiple independent distribution paths so any element can be removed for maintenance without affecting the load, exactly as stated.