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5 minute readData Center Tiers Shouldn’t Cause Tears

Not all Data Centers are the Same

Take a closer look at what data center tiers exist, what they encompass, their respective uptimes/downtimes, and how they are used to make informed business decisions.

Data Center Standards

Data centers provide critical infrastructure to large and small organizations around the world. They house information technology hardware components that are essential to the everyday functions of businesses with varying levels of complexity.

In order to bring an element of clarity into the decision-making process for business and IT leaders, industry standards have been established to provide a rating system for data centers. Specifically, how data centers are rated into tiers.


Data Center Tier Levels per the Uptime Institute

Data center tiers are a standard system for rating data centers in terms of their infrastructure performance, commonly referred to as uptime. Data center tiers are rated from 1 to 4, with higher-rated data centers offering more uptime than lower-rated data centers, per the Uptime Institute.


The Difference Between Tier 1, 2, 3, 4 Data Centers

The Difference Between Tier 1, 2, 3, 4 Data Centers

Tier 1
Basic Capacity Tier 1 Data Centers provide a dedicated space for your IT systems, uninterruptible power supplies (UPSs), controlled cooling, and a generator to keep your equipment running during an extended power outage.
Tier 2
Redundant Capacity Tier 2 Data Centers include all the features of tier 1 DCs plus partial redundancy in power and cooling, which decreases the chances of a power outage or cooling issue becoming a catastrophic disaster that impacts your business’ processing capabilities.
Tier 3
Concurrently Maintainable Tier 3 Data Centers have all the capabilities of tier 1 and tier 2 data centers, but in addition tier 3 Centers allow for power and cooling equipment to be shut down for maintenance without affecting IT processing. To accomplish this, all IT equipment has dual power supplies attached to different UPS units so that a UPS unit can be taken off-line without crashing servers or cutting off network connectivity. Redundant cooling systems are also present so that if one cooling unit fails, the other one kicks in and continues to cool the Data Center.
Tier 4
Fault Tolerance Tier 4 Data Centers incorporate all the features of tier 1, 2, and 3 DCs plus all the power and cooling components are 2N fully redundant. 2N fully redundant means that all IT components are serviced by two different utility power suppliers, two UPS systems, two power distribution units (PDUs), two generators, and two different cooling systems (which are also powered by different utility power services). Fully redundant means that the data and cooling paths are independent of each other. In tier 4 DCs, if any single power or cooling component fails, processing will still continue uninterrupted.


Assessing Data Center Tiers Based on Uptime and Downtime

Uptime is defined as the percentage of time each year that a data center is available. Conversely, downtime is described by the total number of minutes or hours each year that a data center is unavailable.

Assessing Data Center Tiers Based on Uptime and Downtime

Expected uptime percentages, along with the maximum downtime for DCs in each data center tier, are:

  • Tier 1 DCs have a maximum of 1729.2 minutes (28.817 hours) of downtime and 99.671% uptime per year.
  • Tier 2 DCs have a maximum of 1361.3 minutes (22.688 hours) of downtime and 99.741% uptime per year.
  • Tier 3 DCs have a maximum of 94.6 minutes (1.5768 hours) of downtime and 99.982% uptime per year.
  • Tier 4 DCs have a maximum of 26.3 minutes (0.4 hours) of downtime throughout an entire year and 99.995% uptime per year.

Estimated uptime for tier 1 and tier 2 DCs is less reliable while uptime for tier 3 and tier 4 DCs is more reliable because of their high degree of redundancy.


Find the Right Fit

Data center tier ratings provide a helpful set of standards that IT leaders can use to assess risk and plan for the future. Whether you are planning the specifications for your next internal data center or deciding what data center to trust for outsourcing, the tier rating scale will help guide your decision-making.

Specifically, it’s vital to understand your business needs as they relate to the different Data Center tiers. A tier 1 or 2 data center may be the right fit for a smaller company that can tolerate downtime for maintenance after business hours or on the weekends. For these smaller businesses, a tier 3 or 4 DC may not be worth the additional cost. On the other hand, for a large, international company that must stay operational 24 hours a day, 7 days a week by continuously running critical applications, a tier 3 or 4 data center is probably necessary.

The best way we have found to help influence management on these types of decisions is to use the following calculation. We take your annual revenue earned from connected IT infrastructure solutions (say your e-commerce website sales, your call center’s purchase processing system, or CRM) then divide that number by 8,760 (the number of hours in a year). Let’s say your business makes $100M annually, divided by 8,760 then your organization earns $11,416 per hour. That can be used as the amount of revenue you will lose every hour your data center is down.

Estimated Downtime for $100M Example Company
Tier Sigma Max. Down Time (hours) Max. Possible Revenue Lost
1 99.671% 28.817 $328,961
2 99.741% 22.688 $258,995
3 99.982% 1.5768 $18,000
4 99.995% 0.4 $4,566


This calculation can help IT managers explain the importance of Tier 3 or 4 infrastructure.

Reliant Technology Supports World-Class Data Centers Across All Tiers

At Reliant Technology, we support some of the most advanced data centers across all four tiers around the world. With over 15 years of experience, we can provide maintenance and support for at least 50% less than the fees charged by OEMs. Our data center support is fast and responsive because we keep onsite spares kits and respond 24 hours a day, 365 days a year, with a 4-hour SLA.

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Reid Smith-Vaniz

by Reid Smith-Vaniz

Reid is the founder and CEO of Reliant Technology and for 14 years has pursued his mission to remove the pain associated with maintaining IT infrastructure. Reid writes on common challenges related to maintaining, servicing, tracking, budgeting, and upgrading technology.

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Reliant Technology Cares

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About Reliant Technology

As Data Center and storage experts, Reliant Technology is available to provide consultations and solutions to your server backup needs. Our experienced engineers and IT specialists are ready to help you determine the best option for your Data Center. If you have a topic you would like to see discussed, or if you would like to submit an article for possible publication, please, get in touch with us.

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