Data Center Tiers

Understanding data center tiers and types helps IT teams differentiate between the productivity, uptime, construction and design offered by each level. The data center tier classification system can be valuable for companies when analyzing the best specifications to align with business and reliability goals.

The four data center types reflect varying specifications related to performance, redundancy, power sources, etc. With help from the tier classification system, companies can customize IT infrastructure to fit unique industry and compliance needs.

What are Data Center Tiers?

The Uptime Institute established the tier classification system over 25 years ago to create transparency and consistent data center standards. Using the tier guidelines, IT teams can select the relevant performance criteria for their data center infrastructure.

Even if you aren’t seeking a certified tier level, it can be helpful to reference the standards as you consider how to structure your IT infrastructure to meet performance, redundancy and compliance requirements.

Why are Data Center Tiers Important?

The tier classification system reinforces benchmarks to better align your company’s fiscal and performance goals with new infrastructure investments. In many cases, this is viewed as the primary benefit. Tiers can be valuable for:

• Productivity and uptime – When customers rely on software for their business operations, they want reassurance that your data center is redundant. This is especially important for companies that provide Software as a Service (SaaS).
• Credibility and compliance – A data center tier certification proves your organization’s infrastructure is well-equipped to achieve company goals. Each tier is held to rigorous standards, and achieving tier certification puts your data center under review and proves compliance — reassuring stakeholders that their investment is not at risk and that your facility meets their specifications.
• Construction and design – A lot goes into designing a data center, including establishing server locations, power sources, safety measures, etc. When building a new data center or updating an existing one, you can use the tier classification system as a guideline for what elements to include in your system.

Why Data Center Tiers Came About

The data center tier system was implemented in 2005. The Telecommunications Industry Association took a leading role. Their goal was to bring quantifiable standards to an increasingly important industry, that of colocation providers.

The IT industry being what it is, parallel efforts were undertaken as well. A separate tier rubric was created by the Uptime Institute. Fortunately, the differences between the two are minimal and, for most purposes, there is broad agreement on what constitutes a Tier 1 or a Tier 4 data center.

The Data Center Tier Criteria

There are a lot of elements that go into a data center, so each tier ranking reflects multiple criteria. From redundancy to fault tolerance, the tier structure is intended to rank data centers in terms of their achievement to standards, with Tier 4 data centers representing the most robust infrastructure.

The TIA and UI tiers are based on the following:

• Delivery paths for electricity into the building, with more paths providing more reliable electric service
• Redundancy of core components—basically a measure of how many backups are in place for generators, cooling equipment, UPSs, and so on
• Concurrent maintainability, which points to the ability of operations to continue while individual equipment undergoes maintenance or replacement
• Fault tolerance for natural disaster, blackout, and other catastrophes
• Compartmentalization of different pieces of the infrastructure, enabling them to function independently from the rest of the facility
• Availability/downtime measurements in terms of guaranteed availability in the course of a year.

The Differences in Data Center Tier Levels

Although data center tiers officially reflect diverse elements, most clients care most about the guaranteed uptime. Uptime is usually the most critical factor in any service level agreement. The other tier criteria indicate how and why the facility will be able to deliver on its uptime promise, with greater redundancy, fault tolerant, compartmentalized, and otherwise high-quality infrastructure.

It is generally accepted that the tiers represent the following uptime guarantees:

• Tier 1: 99.67%
• Tier 2: 99.74%
• Tier 3: 99.98%
• Tier 4: 99.995%

Although set in terms of uptime, it can be helpful to consider what each tier means in terms of unavailability. For example, a Tier 1 facility is available for all but 28 hours per year. Such facilities or portions thereof may go offline for short periods for scheduled, routine maintenance. Depending on the notice requirements and the business needs, this may have limited impact.

At Tier 3, the client expects only 95 minutes of downtime per year, and Tier 4 sees less than 30 minutes. These are truly high-availability options.

Other core differences in each data center tier are:

• Availability
• Cost
• Efficiency
• Implementation time
• Paths for power
• Redundancy
• Security
• Sustainability
• Uptime

It’s up to the IT specialist to determine their preferred tier standard and which customizations they need to meet business objectives. As the level increases, so do the costs and uptime.

The New Tier 5® Platinum Standard

In 2017, colocation and cloud service provider, Switch, revealed the first-ever Tier 5 data center. This advanced data center features heightened redundancy, long-term power capabilities, zero roof penetrations, physical and network security, 100% renewable energy use and more. To date, the Uptime Institute doesn’t acknowledge Tier 5 data centers in their certification, but the original creators of the standards support the newest tier level.

Industry experts have identified significant threats that affect colocation data centers, including water damage, earthquakes, insufficient security and more. While other data center rating systems don’t consider these elements, Switch created the Tier 5 standard to “reduce the lack of transparency and enhance the reliability of data center rating standards.” The new standard provides their customers increased service and security.

What’s the Right Data Center Tier Level for your Organization?

The tier decision usually comes down to cost-benefit analysis. As the facility’s tier increases, the annual contract costs rise as well, often exponentially.

As a rule of thumb, Tier 1 and 2 data facilities are meant for smaller businesses for which cost is as important a factor as reliability. SMBs are often willing to accept a few hours of downtime here and there, and even the possibility of an unexpected outage, to make ends meet.

Tiers 3 and 4 data centers are the “go to” for larger enterprises and various institutions, such as banks, that require continuous availability and a more complex data center architecture. The consequences of unexpected downtime for a hospital, to take one example, could be life or death. Large internet retailers lose significant revenues whenever a customer cannot complete a transaction, so they often prioritize Tier 4 availability as well.

Choose your Own Adventure

There are also opportunities for blended solutions. In deciding where to house IT hardware and associated functions, it is essential to evaluate business needs and the true cost of failure.

Selecting Tier 4 for everything because “it’s the best” could quickly outstrip reasonable profit margins. Even where Tier 3 and 4 facilities are required for certain IT needs, non-mission critical workloads can often be housed in Tier 1 and 2 centers to lower the associated overhead costs.

Different choices will suit different IT organizations. The tier structure, however, helps facilitate universal “apples to apples” comparisons of cost and options across providers, so each IT department can make the best decision for their particular situation.