What Are Data Center Tiers?

In the simplest of terms, a data center is a physical facility where organizations house their critical applications and data. It’s the powerhouse of your business—the center of your server infrastructure, handling your storage, operations, and the dissemination of data.

Data centers not only guard against data loss and keep your digital operations humming, but they also enable your business to scale seamlessly and efficiently. Without a data center, your operations would suffer from low speed and high risk, causing your productivity and security to plummet. There are different types of data centers—each corresponding to a specific tier. Each tier represents varying levels of redundancy and resilience, which we’ll explore in the next section.

Data Center Tier Summary

Here is a summary of each of the data center tiers. In the table below, we outline each tier and their components in more detail:

Tier ITier IITier IIITier IV
Minimum capacity component
to support the IT load
After any failure
Distrbution paths – Electrical power backbone111 active and 1 alternate2 simultaneously active
Critical power distribution112 simultaneously active2 simultaneously active
Concurrently maintainableNoNoYesYes
Fault toleranceNoNoNoYes
Continuous coolingNoNoNoNo
Data Center Tier Components

Key Terms For Data Center Tiers

The following key terms are helpful in understanding the breakdown of the data center tiering system:

  • Capacity Component: Includes items such as uninterruptible power supply (UPS), cooling systems, and auxiliary generators.
  • Distribution Path: The connection path that a capacity component follows in order to service a server. For example, a power line that feeds from the utility service to a server rack. 
  • Uptime: This is the amount of time that a data center’s services and infrastructure are operational and available to users. It’s generally represented as a percentage, representing the proportion of time the data center is functioning normally over a given period.

Tier I Data Center

Data centers in the Tier I category feature the lowest amount of redundancy and are susceptible to downtime during planned maintenance or sudden disruptions.

Uptime: 99.671%

Power: A single, non-redundant power connection to service the facility.

Cooling: Dedicated cooling equipment.

Fuel Storage: 12 hours.

A Tier I data center offers the most basic level of infrastructure. With a single path for power and cooling and no redundant components, this data center tier is especially vulnerable to disruptions from planned and unplanned issues. As such, it is a good option for data that doesn’t need to be 100% accessible such as cold storage for backups. 

With a guaranteed uptime of 99.671%, they’re a great fit for those with light business demands or non-critical operations. Because a Tier I data center is generally on the lower end, they typically offer lower costs in construction and maintenance protocols.

Tier II Data Center

Data centers in the Tier 2 category feature redundant capacity components with a single distribution path servicing the data centers.

Uptime: 99.741%

Power:  Redundant power such as an engine generator or fuel cells.

Cooling: Redundant chillers, heat distribution equipment, and dedicated cooling.

UPS: Redundant modules.

Fuel Storage: 12 hours of on-site storage for N capacity.

Tier II data centers add redundant components to add a layer of fault tolerance, boosting their reliability in case of emergency. They still only offer a single path for power and cooling, but add uninterruptible power supplies (UPS) modules and generators that are duplicated to further reduce the risk of failure.

Individual components can be taken offline for maintenance in a Tier 2 data center without any downtime, but servers may go offline if the distribution path needs to be taken offline for any reason. A scheduled yearly downtime would be common in Tier 2 data centers, as every component should be shut down for routine maintenance. Without a redundant distribution path, this will often result in server downtime being required.

This data center tier offers 99.741% availability, making it a step up from Tier I. It balances improved reliability without a significant increase in price, making it ideal for businesses that don’t mind occasional downtime but still want improved reliability and availability.

Tier III Data Center

Data centers in the Tier 3 category feature both redundant capacity components (cooling, power, etc.) as well as independent and redundant distribution paths.

Uptime: 99.982%

Power:  Redundant power such as an engine generator or fuel cells. Multiple independent distribution paths to servers. 

Cooling: Redundant chillers, heat distribution equipment, and dedicated cooling.

UPS: Redundant modules.

Fuel: 12 hours of on-site storage for N capacity.

Facilities in this data center tier classification offer significantly higher uptime and operational sustainability. They come with multiple independent distribution paths, though are only used one at a time. Most importantly, a Tier III data center allows for any power or cooling component to be maintained without disrupting operations, leading to an overall higher uptime.

Providing 99.982% availability, Tier III data centers are an excellent choice for organizations that need high availability and 24/7 operations with minimal downtime. However, these do come at a higher price compared to lower data center tiers.

Tier IV Data Center

Data centers in the Tier 4 category, like our London UK Tier 4 Data Center, feature the highest level of redundancy across all levels. These data centers feature multiple independent, compartmentalized, and physically isolated systems to provide redundant capacity components.

Uptime: 99.995%

Power:  Redundant power such as an engine generator or fuel cells. Multiple independent distribution paths to servers. 

Cooling: Redundant chillers, heat distribution equipment, and dedicated cooling.

UPS: Redundant modules.

Fuel: 12 Hours of On-Site Storage for N Capacity

The most advanced of the four, Tier IV data centers offer the highest levels of redundancy and reliability. These facilities have a fully fault-tolerant infrastructure with multiple, independent, physically isolated systems that provide redundant and backup components. They’re capable of withstanding a single unplanned catastrophic event without any operational impact and are equipped for maximum availability.

These data centers have 99.995% availability, making them ideal for mission-critical applications and enterprises where downtime is not an option and operational continuity is essential. While they are the most expensive, they certainly back it up with plenty of features to make it worth the price.

Choosing A Data Center

Picking a data center isn’t as simple as picking Tier IV data centers and calling it a day. There are a ton of factors to consider between data center tiers, each with its pros and cons. Let’s dive into some things you should consider when choosing a data center tier:

  • Business Continuity and Downtime Tolerance: Assess the level of tolerance your business has for downtime. If your operations require high availability and cannot afford frequent or prolonged outages, higher-tier data centers (Tier III or IV) are your best choices.
  • Redundancy Requirements: Consider the level of redundancy your business needs to function. If you need continuous cooling and power without interruptions, a Tier I or Tier II data center wouldn’t be ideal.
  • Scalability and Flexibility: Evaluate the need for future growth and scalability. If your data center infrastructure is going to be upgraded over time, it may be wise to go for a higher-tier data center. They offer better utility for maintenance and are far more scalable than lower tiers.
  • Budget and Cost: Higher-tier data centers involve greater construction and operational costs due to their complex infrastructure and redundancy systems. Make sure your chosen data center aligns with your budget and can offer you a return on investment, or you may be making a costly mistake.
  • Compliance and Security Needs: If your organization is subject to stringent regulatory requirements regarding data security and privacy, a higher-tier data center with advanced security features and compliance certifications might be necessary.
  • Disaster Recovery Capabilities: Consider the data center’s resilience to natural and man-made disasters. Higher-tier data centers are generally designed to withstand such events with minimal impact on operations.
  • Energy Efficiency and Environmental Impact: For organizations focusing on sustainability, the energy efficiency and environmental impact of the data center can be a deciding factor.
  • Technical Support and Services: The availability of expert technical support, managed services, and the quality of customer service are also important considerations. Working with providers that offer excellent support, such as ServerMania, can make a massive difference in the functionality and sustainability of your data center.

At ServerMania, we partner with Tier 3 and Tier 4 data centers in order to ensure maximum uptime for our customers. We also offer a 100% network uptime SLA to host even the most mission critical business applications. Book a free consultation today and find out how ServerMania Tier 3 and Tier 4 data centers can empower your business.