What Are Data Center Tiers (1, 2, 3, 4, 5)?

Posted by Robert Faulkner on March 2, 2023

Not all data centers are created equal. While all data centers must provide certain minimal capabilities to support IT equipment, some go much further to reduce the risk of downtime and other threats. More than 25 years ago, the Uptime Institute developed a system of tiers to provide customers with an independent benchmark for determining how well a particular data center can meet their needs.

Data Center Tier Ratings Explained

Data centers are classified according to five “tiers.” The first four tiers were set by the aforementioned Uptime Institute in the 1990s, while the tier 5 data center standard was established by Switch, a designer, developer, and operator of hyperscale colocation data centers (among other types) across the United States, in 2017. The tiers are determined by factors such as the uptime the facility is expected to deliver, its ability to handle planned and unplanned outages and its cost. The tier standards consider the design and construction of the building itself and the facility’s operational approach. Each level includes the requirements of the levels below it.

The Uptime Institute’s tier certification process includes reviewing facility site plans and conducting onsite visits to examine operations. Tier certifications issued after Jan. 1, 2014, expire after two years. Certification is voluntary, but most major facilities seek a tier rating because it signals to customers that they are committed to meeting the highest standards.

Tier I 

Any facility that has adequate power and cooling to provide basic support for IT equipment. A Tier I data center has few, if any, redundant components and an expected uptime of 99.671 percent. That corresponds to 28.8 hours of downtime each year.

Tier II 

A Tier II data center has some redundant components but still has a single path for power and cooling. The expected uptime is 99.741 percent, which corresponds to 22 hours of downtime each year.

Tier III 

A Tier III data center has multiple paths for power and cooling and the ability to perform maintenance of those systems without taking them offline. It has an expected uptime of 99.982 percent, which corresponds to 1.6 hours of downtime each year.

Tier IV 

A Tier IV data center is the most advanced, with redundancy for every component and complete fault tolerance. It has an expected uptime of 99.995 percent, which corresponds to 26.3 minutes of downtime each year.

Tier V 

The Tier V rating was introduced in 2017 by Switch, a company whose data centers routinely exceeded the Tier IV Gold standard. It goes beyond redundancy and resiliency to mandate the use of renewable energy, 10 or more telecom carriers, the ability to run forever without water, and many other requirements.

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How To Choose the Right Data Center Tier

In order to select the right tier, organizations must balance cost and uptime. It doesn’t make sense to pay for a Tier III data center if Tier II would suffice. By the same token, it isn’t smart to choose a Tier II facility if the potential impact of downtime exceeds the cost savings. 

There are no hard-and-fast rules, but certain types of organizations tend to gravitate toward certain tiers.

  • Tier I is suitable for startups and small businesses that can tolerate downtime and need an affordable option.
  • Tier II data centers are used by many small to midsize businesses that need greater reliability than Tier I.
  • Tier III is a better option for larger organizations that could suffer lost revenue and reputational damage if downtime were to occur.
  • Tier IV facilities are best for larger enterprises with mission-critical requirements.
  • Tier V is for organizations that demand the highest levels of reliability and energy efficiency.

Additionally, organizations should consider customer expectations, security requirements, and legal and regulatory obligations.

Enconnex Delivers Mission-Critical Data Center Infrastructure

A robust data center demands high-quality infrastructure components. As a complete data center and IT infrastructure provider, Enconnex offers everything you need to support and secure your IT equipment, deliver reliable power, and maximize cooling efficiency. 

From server racks and cabinets to aisle containment, network cabling, power cords, power distribution, and more, Enconnex can help you implement a data center infrastructure that meets your requirements now and in the future. Browse our IT and data center products and equipment for sale and get in touch to see how we can optimize your environment. 

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Posted by Robert Faulkner on March 2, 2023

Robert Faulkner is the Vice President of Engineering and Operations at Enconnex. He comes from a strong background in product management with over 20 years in the IT industry. He currently holds an MSME and CDCD certification. He earned his MS degree in Mechanical Engineering at University of Nevada, Reno.

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