ISC2 Certified Cloud Security Professional (CCSP) Practice Question

Uptime Institute defines a Tier III data center as "Concurrently Maintainable." All critical power and cooling capacity components must be duplicated so that any one component can be removed from service without affecting IT operations. This requirement is commonly expressed as an N + 1 configuration: the facility has the needed capacity (N) plus one fully independent spare component to cover a single failure or maintenance event. A simple N design lacks redundancy and cannot meet Tier III. A 2N or N + 2 design provides greater resiliency (full or double-spare redundancy) but exceeds the minimum Tier III specification and is characteristic of Tier IV. Therefore, the least level of HVAC redundancy that satisfies Tier III concurrently maintainable requirements is N + 1.