Data Centre Tiering

What is data centre tiering and why should I consider a tier III data centre?

The Uptime data centre tier standards are a standardised methodology used to determine the availability in a facility. In a nutshell, this means it is easy to establish whether a particular data centre is suitable for the needs of your business as data centres are clearly staged in tiers.

Tier 1

A tier 1 data centre can be seen as the least reliable tier due to the fact that capacity components are non-redundant as well as the distribution path being a single, non-redundant path and as such, if a major power outage or disaster occurs, your equipment is more likely to go offline as there are no backup systems in place to kick in if any issues do occur.

Pros

  • Tier 1 data centres normally provide the cheapest service offering

Cons

  • Single redundancy meaning a considerably lower uptime guarantee than tiers 2, 3 & 4
  • Unplanned outages extremely likely to cause disruption, potentially major
  • Planned outages have the potential to cause issues including equipment downtime. Planned maintenance will often take place at night, which may not be suitable for clients who run their business 24/7 or attract non-UK customers
  • Maintenance and repair work on the facility will require the entire facility to shut down, causing potentially lengthy downtime

Appropriate for:

  • Companies with a passive web marketing presence
  • Small internet based companies with no customer support or e-commerce facilities on-site

Tier 2

Tier 2 data centres are considerably more reliable than tier 1 data centres although they can be subject to problems with uptime. To achieve tier 2, the facility has to meet the criteria achieved with a tier 1 datacentre, as well as ensuring that all capacity components are fully redundant.

Pros

  • Planned service outages can be performed in a way that does not affect equipment uptime
  • Normally cheaper than tier 3 or 4 facilities

Cons

  • A significantly lower uptime guarantee compared to tier 3 facilities
  • Unplanned outages likely to cause disruption, potentially major
  • Maintenance and repair work on the facility will require the entire facility to shut down, causing potentially lengthy downtime

Appropriate for:

  • Internet based companies who can cope with occasional downtime and will incur no penalties for this
  • Companies that do not run 24/7, allowing time for issues to be resolved
  • Higher intensity data driven servers such as model imaging programs

Tier 3

Tier 3 data centres are commonly seen as the most cost effective solutions for the vast majority of medium to large businesses, with availability topping 99.98%, ensuring minimal downtime. To put this figure in perspective, this means that your equipment should see a maximum of two hours of downtime on an annual basis. Tier 3 data centres have to meet all of the requirements of tiers 1 & 2 as well as ensuring all equipment is dual-powered and has multiple uplinks. Some facilities also offer some fully fault-resistant equipment, although to achieve tier 4, all equipment including HVAC, servers, storage, chillers and uplinks must be fully fault-resistant. This tier is generally considered as tier 3+ in the marketplace.

Pros

  • Significantly cheaper than tier 4 facilities
  • Tier 3 facilities offer the most cost-effective solution for the majority of businesses
  • Planned outages will not cause disruption to equipment
  • Unplanned outages unlikely to cause disruption to equipment
  • All equipment required to have dual power inputs, ensuring through one input fails, the other system picks up the slack
  • All maintenance, unless major, can be performed without impact to equipment

Cons

  • Not all equipment fully fault-resistant

Appropriate for:

  • Companies with a worldwide business presence
  • Companies that require have 24/7 operational hours
  • Organisations that require consistent uptime due to financial penalty issues
  • E-commerce and companies running full online operations
  • Call centres
  • VOIP companies
  • Companies with heavy database driven websites
  • Companies that require a constant web presence

Tier 4

A tier 4 data centre is generally considered the most expensive option for businesses. Tier 4 data centres adhere to all the requirement of tiers 1, 2 & 3 as well as ensuring that all equipment is fully fault-resistant. This is achieved by creating physical copies of all essential equipment, otherwise known as N+N.

Pros

  • Tier 4 data centres offer the high availability at over 99.99%
  • Planned & unplanned outages should not cause any disruption to equipment
  • All equipment must be dual-powered
  • All maintenance, unless major, can be performed without impact to equipment
  • All equipment fault-resistant, reducing the likelihood of any lengthy outages

Cons

  • Cost prohibitive for many companies and significantly more expensive than most tier 3 data centres
  • Minimal (under 0.02%) improvement in availability compared to tier 3 facilities

Appropriate for:

  • Large, multinational companies
  • Major worldwide organisations