Everything you’ve ever wanted to know about data center tiers

minute read

Last Updated November 6, 2023

What is a data center?


When you hear or read about data center tiers—what comes to mind? A big multi-level warehouse filled with racks upon racks of twinkling systems? Maybe the scene from the show Silicon Valley, when we meet the socially awkward mole man who’s responsible for keeping the valley’s startups’ infrastructures running? Yup, me too.

While the Silicon Valley scene does a good job of showcasing the enormity of servers it takes to keep our systems going—it doesn’t do much more. (And why would it?)

In this post, I’m taking you behind the scenes to answer these questions:

  • What is a data center?
  • What is a data center tier?
  • What are the differences between data center tier levels?

Let’s get started.

What is a data center?

A data center is a location where an organization or service provider stores data. But there’s a lot more to it than that. In fact, an entire post could be dedicated to defining the various hosting, storage, infrastructure, security and connectivity aspects of data centers.

For the purposes of this post, though, we’ll keep it simple. Think of a data center as a location where data can be hosted, stored, protected and serviced.

What are data center tiers?

There are a lot of data centers out there—and they’re not all equal. The Uptime Institute sets the tier standard for each data center. This standardized system classifies data centers based on their infrastructure, reliability and redundancy levels. There are four main tiers, labeled as Tier I, II, III and IV.

The tier system helps us understand and communicate the reliability and availability of data that’s stored in that facility.

In this post, I’m sharing the facts about the four tiers, as set by the Uptime Institute. Let’s directly compare a few key figures about each level first.


Data center tier levels
Compare the differences in redundancy, availability and cost of data center tiers.

Before diving into the facts about each data center level, let’s define redundancy and availability. These two words are crucial for understanding the overall importance of the tier’s differences.

Data redundancy

When something is “redundant,” it’s repeated or duplicated. When it comes to data, redundancy is super important because it means that your data is housed in multiple locations.

The main advantage of data redundancy is better data availability. If one copy of your data becomes inaccessible, another copy can be used.

Data availability

If something’s available, it means it’s ready for you to use. Seems obvious—right? But when we talk about it in terms of data availability, the tier levels make an enormous difference here.

Compare Tier I to Tier IV; 99.67% vs. 99.995% availability. They seem like close enough figures, but the difference equates to more than 24 hours. That means that if you were using a Tier I data center, you’d be unable to work for over a day. Depending on the business, this could mean a lot of money lost.

“Every minute of downtime can impact your revenue, productivity, customer satisfaction and reputation.” CoreSite

Tier I data center

Tier I data centers are the lowest data center tier level. Typically, they’re what small businesses can afford to use for data storage.

And while they’re better than, say, storing everything on your desktop, they offer a limited number of benefits:

  • Zero redundancy: If the place where your data is stored is hit by a natural disaster or data loss event, there’s nothing anyone can do. That data is gone forever.
  • Unplanned and planned disruptions: Tier I facilities are prone to both planned and unplanned disruptions. If some sort of maintenance is required, your data could go offline for some amount of time. You may know about it beforehand; you may not.
  • Low cost: The benefit of this low-level data center is that it’s not cost-prohibitive, like the higher-level tiers.

If you’re a small business that can afford to be offline for a day or two unexpectedly, and you have a disaster recovery plan in place elsewhere, a Tier I data center may be OK for you.

Tier II data center

Tier II data centers offer a bit more data protection than Tier I, but not by much.

  • Improved infrastructure: Tier II data centers use better equipment and technology at their facilities than Tier I.
  • Some redundancy: Tier II facilities have some power redundancies and offer some cooling but are still susceptible to unexpected interruptions.
  • Low cost: Like Tier I, Tier II facilities are lower in cost. Because of their improved equipment, they are more expensive than a Tier I facility.

Small businesses that can afford to pay a little more for improved data reliability could be satisfied with a Tier II facility. (Still: Consider a separate disaster recovery plan if you use a Tier II data center.)

Tier III data center

A Tier III data center has a higher-level infrastructure with multiple layers of redundancy, called N+1.

We won’t get into the minute technical details of what “N” signifies and the architecture of the technology; however, there are a few key differences to note when it comes to Tier III:

  • N+1 redundancy: In layman’s terms, N+1 redundancy means that if a single component fails, performance is not impacted. The additional “1” would pick up if “N” dropped off.
  • Limited service interruption: Tier III data centers are able to conduct routine maintenance without impacting services.
  • Multiple distribution paths: Basically, if you need to access your data, and one access point is unavailable, you can still get to it. (And you probably won’t even notice a change.)
  • A little pricier: Tier III data centers, as you would expect, are a little more expensive than Tier I and II. This is due to the better infrastructure, improved reliability and availability.

Tier IV data center

Tier IV data centers have the highest level of infrastructure and redundancy. They’re fully fault-tolerant, with multiple independent distribution paths. They offer the best availability (upwards of 99.995%) and can withstand almost any type of failure without downtime.

  • 2N+1 redundancy: This algebraic equation at its base level means this: If an unexpected interruption occurs, there’s another complete infrastructure to take over, in addition to the backup (i.e., you’ll never know if there’s an issue at a Tier IV facility, because your data will stay available).
  • Planned and unplanned events don’t impact users: If scheduled or unscheduled events occur, the other systems pick up to ensure users can continue operating.
  • No single point of failure: Separate distribution paths ensure that if one system fails, the others won’t be impacted (and you’d still be able to access your data.)

The “downside” to Tier IV data centers? They’re pricey. This means that mostly government entities or large global enterprises are their typical customers…unless you’re a Rightworks customer.

About Rightworks’ data center storage

You may have seen the “Tier III and IV data center storage” scattered across our website on product pages, or you may have landed here because you’re just hungry for information about each tier.

Regardless of how you got here, and especially if you are one of the curious folks wondering where and how we store our data or which facilities we use, look no further.

  • All our data, and our customers’ data, is stored in multiple Tier III and Tier IV data centers.
  • We take the precautionary measures of Tier III and Tier IV data centers a bit further by using multiple geographically diverse locations. (If one center fails, the others pick it up.)
  • Our data centers have 99.999% availability—the highest standard of uptime (100% does not exist in the world of uptime). This equates to at most, 5.25 minutes of downtime per year.

There you have it—everything you never knew you needed to know about data centers. Don’t worry, there’s no quiz, but if you’d like to learn more about our technology, feel free to contact us anytime.

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