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What are data centre tier ratings?

October 28th, 2013 Blog, Colocation, How To

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If you’re looking into colocation services, or if you already host your infrastructure in a data centre, you’ll no doubt have come across the term Tier Ratings. But what do they really mean, and why do they matter? Here’s a very quick guide to get you started:

What are tier ratings?

Tier ratings, or rankings, are a system of classification that help to differentiate between the various types of data centre, and the services they offer. The ratings enable you to make a decision on which type of facility best suits your business needs.

Data centre tier ratings were created by the Uptime Institute Also known as the Global Data Centre Authority, the institute is a third-party data centre research, education, and consulting organisation that aims to improve data centre performance and efficiency. They created the data centre tier ratings in order to provide a guide to users on what level of service each centre offers.

What are the different ratings?

Tier I is the most basic form of data centre available. They offer minimal or no redundancy, and power and cooling is provided to equipment via a single path. Down time to your equipment is a possibility and is estimated to be within an acceptable level for business critical applications.

Tier II is the next level up and features redundant components, however still provides only a single path for cooling and power. With this setup it is possible to take some components off-line for maintenance, without disruption to the data processing equipment. However, this will not protect against faults or power outages, and you’ll likely be out of service in this event.

Tier III facilities, offer far greater redundancy as electrical delivery for power and cooling is provided via multiple paths. This means you can take a piece of gear out of service to work on it on a planned basis without upsetting your critical environment. You won’t need to plan for maintenance windows, so you won’t be subject to outages.

Tier IV facilities are the highest rated and offer the best levels of fault tolerance and reliability, as they provide multiple redundancies for each piece of equipment. Multiple independent paths provide power and cooling to all data processing equipment, and any failure or outage will have no significant effect. These types of centre tend to be reserved for companies, such as financial institutions, that would cause a significant economic impact if they experienced down time.

What tier is right for you?

It depends on the type of business you’re operating, what your operational requirements are and what type of infrastructure you have in place. And, of course, whether you can cope with unexpected down time.

What would be the financial impact if your systems were suddenly to go down? And how long could you reasonably cope with such an outage? If an outage is likely to cause a large financial impact for your company, then you’ll need either a Tier II or Tier III data centre. If an outage is not so business critical, then you may find a Tier I centre suits your purposes and could also save you money.

Although these ratings can be a useful guide when it comes to choosing a facility, it’s worth noting that not all data centres are actually certified by the Uptime Institute. To become certified requires significant checks and consultancy – a cost many data centre operators prefer to avoid. As such, many will instead state that their data centre is ‘built and operated to a specific tier standard’ – although this is not actually verified.

Because the operator is likely to be slightly biased it’s worth taking independent advice from people who know the centres, know what service they offer, and can suggest the right type of facility for your business.

What are your experiences of data centre services? Leave a comment and let us know.

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