Posted by Anna Nicholls on 16-Sep-2019 12:06:42

What are data centre tiers?


When you’re choosing a data centre, there’s a lot to consider. Power, location, compliance, accreditations, support…. You need to make sure the data centre you choose fits your needs. Below par, and you could be looking at outages and failure to meet data protection legislation. Over-egg it, and you could be paying through the nose for a level of infrastructure that you don’t need. 

Data centre tiers were designed to help people quickly identify the level of redundancy and complexity that a data centre infrastructure has to offer.  

Data centre tiers definition : a system used to describe different kinds of data centre infrastructure in a consistent way.

Why data centre tiers?
Data centre tiers are a good way of helping you decide whether a particular provider offers a suitable level of resilience for your needs. Tier 1 is the lowest, and Tier 4 offers the greatest level of redundancy. It’s all about assessing the business need, and while a Tier 1 data centre might leave you open to some risk, a Tier 4, for most businesses, can be an over investment.

  • Tier 1 = non-redundant capacity components (single uplink and servers)
  • Tier 2 = Tier 1 + redundant capacity components
  • Tier 3 = Tier 1 + Tier 2 + dual-powered equipment and multiple uplinks
  • Tier 4 = Tier 1 + Tier 2 + Tier 3 + all components are fully fault-tolerant including uplinks, storage, chillers, HVAC systems, servers etc. Everything is dual-powered.

But a Tier rating isn’t always the whole picture. Especially when two or more data centres within the same Tier classification level can vary wildly in terms of actual protection and strength of design. 

For example, a Tier 3 data centre may offer dual rack power from a single N+1 UPS bank on a single power distribution feed, whereas another may offer ‘real’ dual power to the rack with each feed delivered from diverse UPS banks, for far better levels of resilience and protection. So Tier ratings aside, you need to be asking the right questions.

Download our free guide - 10 Questions you should be asking your Cloud Provide for more information.

Tier 1
Because capacity components are non-redundant, a Tier 1 data centre is considered the least reliable. If the data centre experiences a power outage, it’s likely that you will incur downtime due to the lack of backup systems in place. You’ll also be out of action every time the data centre shuts down for maintenance. On the plus side, a Tier 1 data centre should be the cheapest option, so if it fits your business need, then there’s money to be saved. 

Tier 2
A Tier 2 data centre has to ensure that all capacity components are fully redundant. This means that unlike a Tier 1, planned outages for maintenance won’t affect your uptime. However, a Tier 2 will offer a significantly lower uptime guarantee than a Tier 3 or 4 data centre. As you would expect, a Tier 2 should be cheaper than a 3 or a 4, yet more expensive that a Tier 1. If your online services aren’t business critical and you can accommodate some downtime, then a Tier 2 may meet your needs.

Tier 3
For the majority of small - medium sized businesses, Tier 3 data centres are usually a good fit. You should be guaranteed around 99.98%+ uptime guarantee, and often this is financially backed. There should be no downtime for maintenance - unless major work is required. All equipment is dual-powered with multiple uplinks. Tier 3 DCs are considered cost effective, being considerably cheaper than a Tier 4.

Tier 4
This is the top tier - and you’ll pay for it. Tier 4 data centres are your most expensive option, but they offer a 99.99% uptime guarantee. All equipment is fully fault-resistant - achieved by creating physical copies of all essential equipment. This is known in the business as N+N. You should expect no interruption of service for outages - either planned or unplanned. This type of data centre is generally used by large, global businesses or public sector organisations.

Remember, Tier ratings are a guide only. You may find that some Tier 3 data centres offer some of the benefits of a Tier 4, without the high price tag. 

Do your research, and ask the right questions.

If you have any queries, or require more detail on data centre tiers and which level fits best for your business, get in touch with one of our data centre experts here or Book at tour > of our facility to see first hand how our data centre could work for your business. 





Topics: colocation, resilience, cloud hosting, data centre

Written by Anna Nicholls