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Tier 3 Data Centers: What Are They, Exactly?

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Hosting companies often boast about their datacenter facilities.

In the blurb on the website, you'll sometimes see the facility's tier mentioned.

You might notice terms like top tier, or tier 3, usually presented without clear explanation.

So what does this tier system mean - and what's so great about a tier 4 facility?

Understanding Datacenter Tiers

Every datacenter is given a score how much uptime it can guarantee. Tier 1 is the least reliable; tier 4 is the most reliable, but tier 1 and tier 2 typically don't bother with certification so you may not see them mentioned often.

Each tier also has its own specifications. The Uptime Institute developed the tier system and continue to create its definitions.

  • Tier 1: Offers no redundancy at all and guarantees reliability of 99.671%.
  • Tier 2: Adds in redundant components, increasing reliability to 99.741%.
  • Tier 3: Has multiple power and cooling sources, though only one is active at a time. Uptime 99.982%.
  • Tier 4: Everything is dual-powered, including cooling. The site is fault-tolerant and compartmentalized. Uptime 99.995%.

A tier 3 datacenter is very good. A tier 4 datacenter is the norm for mission-critical applications.

What About Bandwidth Tiers?

Many hosts, such as Servint (the host behind this site), talk about getting bandwidth from tier 1 sources.

Don't confuse bandwidth tiers with datacenter tiers: it's a completely different system. For example:

  • There is no certification body for bandwidth tiers.
  • The numbering system is reversed, with 1 being the best - not the worst.
  • Numbering is only assigned on a scale of 1 to 3, not 1 to 4.

On the face of it, it's confusing. But the bandwidth tier rating is actually pretty easy to grasp: it's based around something called peering.

Peering describes the practice of providing bandwidth to other providers for a fee.

  • A tier 1 bandwidth provider is a provider that doesn't pay for bandwidth - it's independent.
  • A tier 2 provider peers with some network capacity but pays for access to the rest.
  • A tier 3 provider purchases all access from a third party - it is reliant on peers for its capacity.

Tier 1 bandwidth providers are considered to be the fastest and most reliable. However, hosts often have multiple providers, so the issue is rarely clear cut.

Confused? Don't be. Just remember that overall, lower tiers are better when it comes to bandwidth, but it's not a crucial measurement of quality.

How Much Do Tiers Matter?

The short answer is 'not much'. Look at the uptime figures in the datacenter tier list: you're not going to see a massive improvement between tiers, and tier 4 datacenters are so expensive as to be out of the reach of anyone but the enterprise customer.

Looking at bandwidth, the tier matters less than the redundancy and speed. Look for multiple connections and adequate high-speed bandwidth rather than relying solely on the tier system. There are many other important factors in determining the speed and reliability of a host, such as its location relative to your visitors.

(Thanks to pzado for the image)

Claire Broadley

About Claire Broadley

Claire has been creating websites for over 20 years and has been using WordPress for over ten. She is an expert in web hosting, design, HTML, and more. She lives with her husband and son in the United Kingdom.


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Paul Marshall

October 10, 2017

I think the additional cost of a Tier 4 system makes them prohibitive, but I also think not all Tier 3 systems are the same. There’s a greater range of providers offering Tier 3 services but some have invested more heavily in their infrastructure than others and it’s well worth doing the extra research before selecting a partner.