Data Center Tier: The Difference of Tier 3 and Tier 4

by Luis Andrianto SEO Specialist

Data center tier is a level of system that is designed by the Uptime Institute. This way is used so that people can identify the different data center in effective and simple way. There are four Tiers which are classified by the Uptime Institute. Each of the tier has different characteristics. Every level also shows the certain number of guarantees about the type of hardware used in the data center. It has something to do with the redundancy.

The availability of tier 1 is 99.67%, which means 28.8 hours of unavailability for a year. There is no redundancy for this level. The availability of the Tier 2 is 99.75%. It means that there will be 22 hours of unavailability for one year. In Tier 2, you will find partial redundancy. In Tier 3, the availability is 99.982%, which means there will be 1.6 hours of interruption for one year. The redundancy is N+1. The last we have is Tier 4 which the availability is 99.995%. It means that the interruption is 0.8 hours for one year. The redundancy is 2N+1.

In data center tier, level one and level two use single path for both cooling distribution and power. Level one comes without redundant components, while level two has redundant components. Tier 3 and Tier 4 use multiple cooling distribution paths and multiple active powers. Both of them have redundant components.

In Tier 3, you will be able to manage the period of maintenance without disturbing the continuity of the service. Yet, this level of data center will not be protected from outages. Thus, when serious incidents happen in different infrastructure components, the server will not be protected. We can say that Tier 3 does not have total modular redundancy. Tier 4 is known as the highest level of guarantee. This level is fully redundant in its cooling system, network, and also electrical circuits. The server availability can still stand even in worst situation.