Data Centre Tiers Explained

March 15, 2010 - PRLog -- An explanation of the Tier classification of Data Centres

Data Centre Tiers

Tier 1 Data Centre

A Tier 1 data centre is classified as one with a basic site infrastructure. This means a single distribution path serving the resident computer equipment and non-redundant capacity components. As the most basic tier of data centre, computer equipment at this site will be susceptible to disruption if any component or capacity system were to fail unexpectedly. Disruption will also occur annually when the entire site infrastructure is required to be totally shut down for maintenance and repair work. Unplanned maintenance or repair of any single component or system would also cause widespread disruption or failure.

Tier 2 Data Centre

A Tier 2 data centre is required to have redundant capacity components and a single non-redundant distribution path to serve the computer equipment within. With the backup of redundant capacity components, any redundant component can be moved from service on a planned basis without any of the other systems failing. This is not the case in the Tier 1 data centre.

As with a Tier 1 data centre, human operational errors of the site’s components are likely to cause a disruption to data centre operations. An unplanned outage may also effect hosted computer equipment. A Tier 2 data centre must also completely shut down its systems on an annual basis to perform maintenance work.

Tier 3 Data Centre

A Tier 3 data centre will have both redundant capacity components and multiple, independent distribution paths to serve computer equipment. Each component and distribution path element can be removed from service without having any effect on computer equipment. Although a Tier 3 data centre must have sufficient permanently installed capacity to continue operations if any redundant component is removed, it is still susceptible to disruption from operational errors. Planned site infrastructure maintenance can however be performed without any disruption to remaining equipment.

Tier 4 Data Centre

The highest level of tier, a Tier 4 data centre is fault tolerant with multiple, independent and isolated systems serving the computer equipment stored within. Power and cooling is provided to the equipment in the event of any failure. With compartmentalised systems, a single unexpected failing of any system component will not impact the computer equipment. What’s more, the system will itself respond to the failure as a means of preventing equipment damage. As with the Tier 3 data system, maintenance work can be carried out without shutting down the system or impacting on operations. Continuous cooling must be provided in a Tier 4 data centre.

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