Data Center Tier Levels

What Does Data Center Tier Levels Mean?

Data center tier levels refer to a data center’s ability to maintain functionality during various kinds of failures, such as power outages. Higher tier levels indicate more sustainability for data center operations and fault-tolerant systems that will allow for uninterrupted use during certain kinds of emergencies or crises.


As more advanced technology has led to greater evaluation of fault tolerance for data systems and other business processes, the global IT community has defined data center reliability by referring to up to four tiers for data center operations. Groups such as the Uptime Institute, a global research organization, have defined these tiers and provided certifications for data center systems.

Techopedia Explains Data Center Tier Levels

In a Tier 1 data center, system processes are carried out through a single path in a nonredundant system that does not offer fault tolerance. In a Tier 2 system, there may be some redundant features, for example, in climate and energy source support. Tier 3 systems will typically have more comprehensive protections for power outages and will have what’s called N+1 redundancy, which is a reliable backup power system. The highest level, Tier 4, will involve fully fault-tolerant systems around energy supply, storage and data distribution and backup power sources for climate control systems. These specifications for data center sustainability help to create a consistent standard in the business world where vendors, clients and others typically refer to these various tier levels when planning, creating and implementing data centers in individual corporate or small business environments.


Related Terms

Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.