Data center tiers are an effective approach to characterize the infrastructure components used in a company's data center. Although a Tier 4 data center is more complicated than a Tier 1 data center, this does not always imply that it is best suited to the demands of a business. While investing in Tier 1 infrastructure may expose a company to danger, investing in Tier 4 infrastructure may be an over-investment.

Tier 1

A Tier 1 data center has a single path for power and cooling and few, if any, redundant and backup components. It has an expected uptime of 99.671% (28.8 hours of downtime annually).

Tier 2

: A Tier 2 data center has a single path for power and cooling and some redundant and backup components. It has an expected uptime of 99.741% (22 hours of downtime annually).

Tier 3

A Tier 3 data center has multiple paths for power and cooling and systems in place to update and maintain it without taking it offline. It has an expected uptime of 99.982% (1.6 hours of downtime annually).

Tier 4

A Tier 4 data center is built to be completely fault tolerant and has redundancy for every component. It has an expected uptime of 99.995% (26.3 minutes of downtime annually).