When researching data center providers or reviewing plans to build out your own, it’s likely you’ve come across the Uptime Institute's Tier classifications for data centers. Ranging from Tier I to Tier IV, these classifications are considered the industry standard to determine the availability of a facility.
To earn the highest Tier rating of IV, a data center must meet certain operational complexities — assuring its clients a higher rate of uptime. Data time availability requirements range from 99.671 percent uptime for Tier I facilities to 99.95 percent uptime for Tier IV facilities. The certifications, which are progressive — with the higher Tier rating including all features of the previous rating, are as follows:
Tier I: A Tier I data center can provide basic capacity for a company that does not have complex needs but wants a dedicated space for IT systems; an uninterruptible power supply; and dedicated cooling equipment. The availability rating for a Tier I facility is 99.671 percent.
Tier II: With a Tier II facility, you’ll gain the benefit of redundant capacity components, including power and cooling equipment. These guard against IT process disruptions that would result from site infrastructure equipment failures. A Tier II facility has an availability rating of 99.741 percent.
Tier III: A Tier III data center, which has an uptime rating of 99.982 percent, does not require a shutdown to replace equipment or for maintenance — assuring ongoing IT operations.
Tier IV: Labeled as fault tolerant, Tier IV site infrastructure is the highest rated, with an uptime rating of 99.95 percent. In addition to all the qualities of the other Tier rated structures, a Tier IV facility assures that IT operations aren’t impacted in the event of individual equipment failures or other interruptions.
According to Uptime Institute, the Tier Certification process can be extensive, with the company defining a need for a specific Tier Level to meet demand. Data center providers also may want to take on the process to incorporate the changes necessary to move up to another Tier Level.