Data Center Classification

TIA-942 (Telecommunication Industry association) standard provide classification of data center based on availability tiers. The classification of tiers allows users to compare one data center with other objectively and allows designer to built data center as per defined service availability. The tier 1 is basically a server room with basic systems. As the tier goes up the specifications become stringent with tier 4 providing security and redundancy catering to the needs of running mission-critical applications.


The requirements for all the four types of Tiers are given in table below:


Data center Parameters

Tier I

Tier 2 Tier 3 Tier 4
Availability components

Basic site infrastructure with no redundant components

Redundant site infrastructure

Concurrently maintainable site infrastructure

Fault Tolerant site infrastructure






Operational Impact

System maintenance or failures can cause disruptions

Less susceptible to disruptions due to system maintenance or failures

No disruptions in case of planned activity but unplanned event can cause disruptions

No disruptions in case of planned maintenance or single unplanned event.

Power systems

Single power connection. No redundancy of

Components for power systems or cooling. May or may not have or

Single power connection. The power component are provided with (N+1) redundancy

Multiple power connections single active path. The power component are provided with (N+1) redundancy

Multiple active power paths,

With redundant components in 2 (N+1) configuration.

Infrastructure requirements

Optional raised floor, diesel generator, UPS

Must have raised floor, diesel generator and UPS.

The power system should run on single path so that maintenance can be done on another path without disrupting the operations.

Must have raised floor. Maintenance activity on any subsystem does not disturb working of the system

Implementation schedule

Around 3 months

Around 3 to 6 months

Around 15 to 20 months

Around 15 to 20 months

Max down time specified

28.8 hrs. per annum

22.0 hrs. per annum

1.6 hrs. per annum

0.4 hrs. per annum


The complete information in the above table is available with figures and you can check the classifications are done by the efficiency and processing speed. There are very minor changes in the each tier but when it goes live it will much effects on the processing and time period.

You can also keep up to date with current trends and technology by visiting Data Center Talk where we keep you informed on important changes as they occur.