Data Center Tiers

What exactly is a data center?

A commercial data center (or datecenter or data centre) is facility designed to house computer servers at a climate-controlled environment. It is built to withstand calamities and environmental disasters such as storms or fires. Data centers are equipped with redundancy systems that can constantly produce clean power such as uninterrupted power systems (UPS). The best data centers ensure continuous operation in virtually any circumstance.

Enterprise class data centers are ideal for large organizations that need to share data between various divisions that do not share the same physical presence. By hosting data in a climate-controlled environment,you can minimize the cost of sharing data between various divisions of the same organizations. A wholesale data center provider rents / leases space to businesses and individuals who wish to host data in a controlled environment.  This kind of arrangement can disperse the cost of building storm-resistant and climate-controlled structures,thus providing all tenants with maximum reliability.

Since data centers are designed to house sensitive computing equipment,they usually have several elements in common. Each data center comes with physical security,fire suppression,environment control,stand-by power,and plenty of computing equipment. As the center of computer operations,datacenters need to be properly designed to minimize the risk of losses due to disasters and facilitate efficient disaster recovery efforts as well.

Standards for data center tiers

The Uptime Institute,an organization based in Santa Fe,New Mexico,defines and holds the copyright to the four Tier levels,the Tier Classification (Tier I,Tier II,Tier III,Tier IV) were created to describe site-level infrastructure required to sustain data center operations.

Tier I:Basic

  • Non-redundant capacity components and a single distribution path to IT equipment.
  • 12 hours of on-site fuel storage
  • Planned work will require most/all of the site infrastructure systems to be shut down.
  • Susceptible to disruption from both planned and unplanned activities.

Tier II:Redundant

  • Fulfills Tier 1 requirements
  • Redundant capacity components and a single distribution path to IT Equipment.
  • Redundant components can be removed on a planned basis without causing any of the IT equipment to be shut down.
  • Susceptible to disruption from planed and unplanned events.
  • 99.741% availability

Tier III:Concurrently Maintainable

  • Fulfills Tier 1 and Tier 2 requirements
  • Redundant capacity components and multiple independent distribution paths
  • Each and every capacity component in the distribution path can be removed for service on a planned basis without impacting any IT equipment.
  • Susceptible to disruption from unplanned activities.
  • 99.982% availability

Tier IV:Fault Tolerant

  • Fulfills Tier 1 and Tier 2  and Tier 3 requirements
  • Multiple,independent,diverse,active distribution paths.
  • ‘N’ capacity for power and cooling to the IT equipment after any infrastructure failure
  • Not susceptible to disruption from a single unplanned event.
  • 99.995% availability
TIER REQUIREMENTSSource:The Uptime Institute
Tier ITier IITier IIITier IV
Number of delivery paths (power and cooling)Only 1Only 11 active
1 passive
2 active
RedundancyNN+1N+12(N+1) or S+S
Concurrently MaintainableNoNoYesYes
Fault tolerant to worse eventNoneNoneNoneYes
TIER REQUIREMENTSSource:The Uptime Institute
Tier ITier IITier IIITier IV
Building typeTenantTenantStandaloneStandalone
StaffingNone1 Shift1+ Shifts“24 by forever”
Useable for critical load100% N100% N90% N90% N
Initial watts per square foot20-3040-5040-6050-80
Ultimate watts per square foot20-3040-50100-150150+
Uninterruptable coolingNoneNoneMaybeYes
Support space:raised floor20%30%80-90%100+%
Raised floor height12″18″30-36″30-36″
Floor loading pounds per SF85100150150
Utility voltage208,480208,48012-15kV12-15kV
Single points of failuremany + human
many + human
many + human
many + human
Annual site-caused IT downtime (actual)28.8 hrs22.0 hrs1.6 hrs0.4 hrs
Site availability99.671%99.749%99.982%99.995%
Months to Implement33 to 615 to 2015 to 20
Year first deployed1965197019851995