Term Kind Topic What it is
Availability Arithmetic concept Availability Mathematics Multiplying dependency availabilities in series and combining redundant components in parallel to derive a system's achievable availability.
Availability Composition concept Availability Mathematics How the availability of a system follows from its dependencies — multiplying for serial dependencies and improving sharply for redundant ones.
Nines Table concept Availability Mathematics The mapping between availability percentages and permitted downtime, and the cost curve that comes with it.