Data Center Tiers

Introduction

A data center is a facility used to house computer systems and associated components such as telecommunications and storage systems. It generally includes redundant or backup power supplies, redundant data communications connections, environmental controls (e.g., air conditioning, fire suppression, etc.), and security devices. 6

There have been various methods introduced throughout the mission critical facility industry, such as The Uptime Institute’s Tier Performance Standards. Data Center Tiers are used to measure the performance of data center through levels of criticality.

Tier 1 to 4 data center is a standardized methodology used to define uptime of data center. This is useful for measuring: 7

  • Data center performance
  • Investment
  • Return on Investment (ROI)

It is a four-tier system that provides a simple and effective means for identifying different data center site infrastructure design topologies. 8

  • Tier 1 – Non-redundant capacity components (single uplink and servers). It is composed of a single path for power and cooling distribution, without redundant components, providing 99.671% availability.
  • Tier 2 – Tier 1 + Redundant capacity components. It is composed of a single path for power and cooling distribution, with redundant components, providing 99.741% availability.
  • Tier 3 – Tier 1 + Tier 2 + dual-powered equipments and multiple uplinks. It is composed of multiple active power and cooling distribution paths, but only one active path, has redundant components, and is concurrently maintainable providing 99.982% availability
  • 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. It is composed of multiple active powers and cooling distribution paths, has redundant components, and is fault tolerant, providing 99.995% availability.  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.

Requirements 9

Tier 1

  • Single non-redundant distribution path serving the IT equipment
  • Non-redundant capacity components
  • Basic site infrastructure guaranteeing 99.671% availability

Tier 2

  • Fulfils all Tier 1 requirements
  • Redundant site infrastructure capacity components guaranteeing 99.741% availability

Tier 3

  • Fulfils all Tier 1 and Tier 2 requirements
  • Multiple independent distribution paths serving the IT equipment
  • All IT equipment must be dual-powered and fully compatible with the topology of a site’s architecture
  • Concurrently maintainable site infrastructure guaranteeing 99.982% availability

Tier 4

  • Fulfils all Tier 1, Tier 2, and Tier 3 requirements
  • All cooling equipment is independently dual-powered, including chillers and Heating, Ventilating and Air Conditioning (HVAC) systems
  • Fault tolerant site infrastructure with electrical power storage and distribution facilities guaranteeing 99.995% availability

Conclusion

Tier Level Classification system is the foundation used by many data center owners/users, consultants and design professionals in establishing a “design-versus performance” ranking approach to today’s data center projects. 10

Tier Levels provide an objective basis for comparing the capabilities of a particular design topology against other designs as well as the associated site availability metrics for the various levels 11. Tier levels are chosen as per the level of criticality. The simplest is a Tier 1 data center used by small businesses or shops. Tier 4 data center is considered as most robust and less prone to failures.

6 en.wikipedia.org
7 cyberciti.biz
8 webopedia.com
9 en.wikipedia.org
10 peci.org
11 peci.org