Data Centre Tiers Explained
In this post we explain the difference between a Tier 1, Tier 2, Tier 3, and Teir 4 Data Centre.
The Tier number (1 to 4) defines the resilence and uptime of the centre. Tier 4 data centres are considered the most robust and least prone to failures. Tier 4 is designed to host mission critical servers and computer systems, with fully redundant subsystems (cooling, power, network links, storage etc) and compartmentalized security zones controlled by biometric access controls methods.
Tier 1 = Non-redundant capacity components (single uplink and servers).
Tier 2 = Tier 1 + Redundant capacity components.
Tier 3 = Tier 1 + Tier 2 + Dual-powered equipments and multiple uplinks.
Tier 4 = Tier 1 + Tier 2 + Tier 3 + all components are fully fault-tolerant including uplinks, storage, chillers, HVAC systems, servers etc. Everything is dual-powered.
Data Center Availability According To Tiers
The levels also describes the availability of data from the hardware at a location as follows:
Tier 1: Guaranteeing 99.671% availability.
Tier 2: Guaranteeing 99.741% availability.
Tier 3: Guaranteeing 99.982% availability.
Tier 4: Guaranteeing 99.995% availability.