TierAvailabilityDescription
Tier I99.671%Basic capacity, no redundancy
Tier II99.741%Redundant components, partial redundancy
Tier III99.982%Concurrently maintainable, fully redundant
Tier IV99.995%Fault-tolerant, fully redundant
FactorIn-HouseColocationCloud
Upfront costHigh (CAPEX)MediumLow (OPEX)
ControlFullSharedLimited
ScalabilityLimitedMediumHigh
ComplianceEasiestGoodVaries
Operational burdenHighestSharedLowest