Data Center Tiers: A Quick Guide

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Data center tiers represent the level of its service. Almost every data center has a tier ranking of I, II, III, IV. These tiers act as an indicator of what the data center has to offer, its physical infrastructure, its cooling, uptime, power capabilities, redundancy and so on. Let’s take a look into what each tier has, but before that let’s take a look at their origin:

2005-Tiers Came Into Existence

The data center tier system originated in 2005 to bring a set of standards to the industry against which the data centers can be assessed. Telecommunications Industry Association (TIA) was the body who developed these standards. Besides, the Uptime Institute has also developed a separate 4-tier level.

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It is the simplest of the 4-tiers, offering fewer (if any) levels of redundancy. They need a dedicated space for all the IT systems which may be a server room that may or may not have locks. They have the UPS systems in place to ensure a consistent supply of power which also prevent the systems from any spikes from damaging the hardware. They also have a controlled cooling environment that runs round the clock. Besides, they also come with a generator system that provides power whenever there is an extended outage. They usually claim to offer extended uptime levels of 99.671 %.


A Tier-2 data center has all the features plus there are much more things to it. They offer some redundancy in power and the cooling systems that make them less susceptible to unplanned downtime. So with tier-2 data systems, you can rest assured that the data center will not shut down as there is no power. They offer expected uptime levels of 99.741%.


In a tier-3 data center, you will find all the features of tier-1 and tier-2 data centers. Besides, it also wants that, any power and the cooling system can be shut down for the maintenance without having any effect on the IT operations. Every equipment must come with dual power supplies. They must be connected to two different UPS units in such a way that if a UPS unit is taken-offline, there is no effect on the operations of the servers. The cooling systems must also be redundant so that if one system fails, the other starts working and the room temperature is maintained.  These data centers are not considered fault tolerant as they usually share components that reside out of the data center. They offer the expected uptime levels of 99.982%.


In a tier-4 data center, you’ll find all the features that of a tier-1, tier-2 and tier-3 data center. In addition to this, all the tier-4 power and cooling components are completely redundant which means that all IT components have dual power supplies, two generators, two UPS systems, two units for distribution and two units for cooling. Both cooling and the data paths have redundancy. In a tier-4 data center, if any of the single power or the cooling components fail the data center continues to operate. The IT operations come to a halt only when all the electrical components fail simultaneously.

data center tiers

Source – Visually

How May These Tiers Be Important For You?

Once you have understood their tiers, it is important to understand the importance of the various tiers for the business. A tier-1 and tier-2 data center may work well for the smaller firms as they may not need round the clock services and almost zero downtime. But for large multinationals that need to be up and running round the clock and need 100% uptime, tier-3 data center and tier-4 data centers are the best.

Wrapping Up

So data center tiers help you decide what you can expect from the data center for your business. It is better to understand what these tier offer before building a data center.

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Data Center Tiers: A Quic…

by Sandeep Srivastava time to read: 3 min