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Tier 3 Data Center: What Is It and Why Choose It?

Updated on May 27, 2019 by
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Created by the Uptime Institute, data center tiers are an efficient way to describe the infrastructure components that are utilized at a specific data center. The classification is recognizable in the industry as the standard to follow for data center performance. Tier 1 is the simplest infrastructure, while Tier 4 is the most complex. This article focuses on explaining Tier 3 data centers. What is a Tier 3 data center? What are the benefits of choosing it?

data center tiers

Features of a Tier 3 Data Center

A Tier 3 data center is a concurrently maintainable facility with multiple distribution paths for power and cooling. Unlike Tier 1 and 2 data centers, a Tier 3 facility does not require a total shutdown during maintenance or equipment replacement.

A Tier 3 facility requires all the components present in a Tier 2 data center, but these facilities must also have N+1 redundancy:

  • "N" refers to the necessary capacity to support the full IT load.

  • "+1" stands for an extra component for backup purposes.

N+1 redundancy ensures an additional component starts operating if the primary element runs into a failure or the staff removes the part for planned maintenance.

Tier 3 data centers also require a backup solution that can keep operations running in case of a local or region-wide power outage. The facility must ensure equipment can continue to operate for at least 72 hours following an outage.

features of Tier 3 data center

Tier 3 data centers have a significant jump in availability when compared to lower ratings. Customers that rely on a tier 3 data center experience an expected uptime of 99.982% (1.6 hours of downtime annually).

Benefits of Choosing a Tier 3 Data Center

No disruption to equipment

If a company is experiencing frequent interruptions and increasing downtime, they might desire to upgrade to a more fault-tolerant system. Compared to Tier 1 and 2 facilities, Tier 3 data centers are ranked high in data center reliability as concurrent maintenance is built into the site’s topology. This inherently limits the effects of the disruption before it reaches IT operations. For mission critical applications and systems, this increase in reliability can become paramount and effective to necessitate an upgrade from Tier 2 to Tier 3.

No shutdown during maintenance or replacement

Tier 3 data centers have N+1 redundancy, which means an additional component starts working if the primary element runs into a failure or is removed by staff for planned maintenance. Multiple power circulation paths and capacity equipment are supplied with simultaneous energy. Unlike Tier 1 and Tier 2, these facilities require no shutdown when maintenance or replacement is needed, so IT operations will not be impacted.

Affordable than Tier 4 data centers

A Tier 4 data center is an expensive option for businesses. It has all the requirements of Tiers 1, 2 & 3 and ensures that all equipment is fully fault-resistant. Tier 4 data centers serve corporations and are packed with features such as 99.995% uptime (26.3 minutes downtime annually) and 2N+1 fully redundant infrastructure. While Tier 1 and 2 data centers might not be up to standards and cannot support complex features required by businesses due to their simpler infrastructure. In this sense, Tier 3 data centers might come as an optimal choice as they are more affordable than Tier 4 data centers and still offer impressive features.


Typically, Tier 3 data centers are the ideal choice for large companies with complex IT requirements that need extra fail-safes. Businesses that host critical and extensive databases, especially customer data, usually go for this tier. We hope this article can help you learn more about Tier 3 data centers and choose the best-suited tier for your business.

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