Tier 3 and Tier 4 Data Centers

Why and When You Should Move from a Tier 3 to a Tier 4 Data Center

In our environment of seeking continual optimization and improvement, data centers have not escaped evaluation. In fact, because of their crucial IT functions, data centers can merit extra scrutiny.

How, then, are data centers evaluated?

In the 1990s, The Uptime Institute began to put forward a sequence of tier classifications that systematized data centers.

The Classification Tiers

This system rates data centers into various tiers, also known as levels. It has implications for uptime, downtime, mean time between failures (MTBF), mean time to repair (MTTR), and the effects (or lack thereof) of disruptions, including outages and planned or unplanned maintenance.

A Tier 1 and Tier 2 rating indicates that the systems are operational and hold some benefits. A Tier 3 system has features that are often beyond current IT requirements. A Tier 4 system continues to improve on the function of a Tier 3 system with some additional key features.

Tier 3 versus Tier 4

Tier 3 classification has many benefits just as Tier 4 systems also have advantages. How can a company know when it might be time to upgrade.


Your company might consider a Tier 3 to Tier 4 upgrade if the reason for the data center’s function requires the switch. As a company might develop international capacities, more complex functions might be required as international brands often merit the insurance of Tier 4 functionality. Additionally, as traffic levels may increase or processing demands grow, the key features of a Tier 4 classification might outweigh the implementation cost and fiscal price of such a switch. Growth or developmental reasons may influence a company’s desire to upgrade to the enterprise-level service offered by Tier 4 systems.


If a company is experiencing frequent interruptions and increasing downtime, they might desire to upgrade to the most fault-tolerant system possible. Tier 4 options are ranked highest in data center reliability as fault tolerance 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 3 to Tier 4.


Tier 3 data centers have greatly improved redundancy capacities compared to Tier 1 and Tier 2 systems. Tier 3 systems have an uninterruptible power supply (UPS) as an N + 1. This effectively means that the center maintains the typical system while still having another available for backup. However, a Tier 4 system expands on this. Tier 4 systems have 2N + 1  functionality. This means that they have two times the amount of required backup when maintenance or planned or unplanned disruptions result. It maintains a redundant capacity for every component, and this can be reason for companies to seek such a Tier 4 upgrade.

The benefits of a Tier 3 system compared to that of a Tier 1 or Tier 2 system are substantial. However, the benefits of a Tier 4 rating over a Tier 3 rating are also consequential. Although there are many benefits to a Tier 4 system, the costs are also high. Implementation and financial costs do incur. In some cases, such tangible and intangible costs of a Tier 4 system will not merit a switch from the high-capacity workload Tier 3 option. Yet, in other cases, companies might find that they are ready to make the move and experience the benefits to their data center configuration.

To find out more about data center management, including data center infrastructure management, hybrid digital infrastructure management, center improvement strategies, the Data Center Optimization Initiative, and more, check Nlyte Software Solutions.



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