Data Center - Data Center Tiers

Data Center Tiers

The Telecommunications Industry Association is a trade association accredited by ANSI (American National Standards Institute). In 2005 it published ANSI/TIA-942, Telecommunications Infrastructure Standard for Data Centers, which defined four levels (called tiers) of data centers in a thorough, quantifiable manner. TIA-942 was amended in 2008 and again in 2010. TIA-942:Data Center Standards Overview describes the requirements for the data center infrastructure. The simplest is a Tier 1 data center, which is basically a server room, following basic guidelines for the installation of computer systems. The most stringent level is a Tier 4 data center, which is designed to host mission critical computer systems, with fully redundant subsystems and compartmentalized security zones controlled by biometric access controls methods. Another consideration is the placement of the data center in a subterranean context, for data security as well as environmental considerations such as cooling requirements.

The German Datacenter star audit program uses an auditing process to certify 5 levels of "gratification" that affect Data Center criticality.

Independent from the ANSI/TIA-942 standard, the Uptime Institute, a think tank and professional-services organization based in Santa Fe, New Mexico, has defined its own four levels. The levels describe the availability of data from the hardware at a location. The higher the tier, the greater the availability. The levels are:

NOTE: The difference between 99.982% and 99.995%, 0.013%, while seemingly nominal, it could be significant depending on the application. Looking at one (1) year or 525,600 minutes, in expectation, T3 will be unavailable 94.608 minutes whereas T4 will only be unavailable 26.28 minutes. Therefore, T4 in a year will be available for an expected 68.328 more minutes than T3. Similarly, a T3 data center would be expected to be 22.6 hrs more available than a T2.