What type of redundancy provides two additional units, modules, paths, or systems in addition to the MINIMUM required to satisfy the base requirement.

N represents exactly the minimum required with zero spare capacity, meaning any single failure results in a service interruption.

N+1 adds only one additional unit beyond the minimum, tolerating only a single simultaneous failure rather than two.

In the N+x redundancy notation, N represents the minimum number of components required to satisfy the base operational requirement, and the suffix indicates additional spare capacity. N+2 therefore means two extra units, modules, paths, or systems are deployed beyond the minimum, so two concurrent failures can occur without impacting the supported load.

2N is a fully mirrored configuration that doubles every component, which provides more redundancy than N+2 but is not defined as two additional units.

2(N+1) doubles the sum of the minimum plus one, representing a higher tier of redundancy than N+2 and is not the definition of two additional units.