Data Center Tier Classification
In this article, we are introducing the data center tier classification. The tier classification is used to describe the infrastructure components of the data center where Tier 1 is the simplest infrastructure and Tier 4 is the most complicated. Tiers are not a way to describe how good a data center is. Each tier of the four serves different business operational requirements and uptime levels. As you might expect, higher reliability relates directly to higher construction costs. Sometimes, the desired
availability level becomes unrealistic, once the financial commitment is fully realized. At the very least, the Uptime Institute’s tier specifications turn out to be a tremendous value to planners as they have become a uniform method for evaluating specifications, determining initial budget estimates and communicating requirements to architects and engineers.
Below are the 4 tiers of data centres according to Uptime Institute:
Tier 1 Data Center
- Downtime per annum: 28.8 hours
- Redundancy: Zero
- Uptime per annum: 99.671%
Tier 1 data centre implements a single path for power and cooling and few to none redundant and backup components. They are the ideal solution for a small business since they are cost-effective. The requirements for a Tier I facility are very basic and they include:
- An uninterruptible power supply (UPS) for power sags, outages, and spikes.
- An area for IT systems.
- Dedicated cooling equipment that runs outside office hours.
- A generator for power outages.
To perform planned maintenance in a tier 1 data centre, a full shutdown is necessary and an unexpected failure of a component will affect the system.
Tier 2 Data Center
- Downtime per annum: 22 hours
- Redundancy: Partial cooling and multiple power redundancies
- Uptime per annum: 99.741%
Tier 2 data centre single path for power and cooling and some redundant and backup components, which allows it to serve a critical environment, and the components can be removed without shutting it down, but the unexpected failure will affect the system. They are mostly utilized by SMBs. The requirements for a Tier 2 facility are very basic and they include:
- Engine generators.
- Energy storage.
- Chillers.
- Cooling units.
- UPS modules.
- Pumps.
- Heat rejection equipment.
- Fuel tanks.
- Fuel cells.
Tier 3 Data Center
- Downtime per annum: 1.6 hours
- Redundancy: Partial cooling and multiple power redundancies
- Uptime per annum: 99.982%
- Power Outage Protection: 72 hours of protection
- Fault Tolerance: N+1
Most data centre companies that are ranked by Uptime Institute have Tier 3 ranking.
Tier 3 data centres are concurrently maintainable, with redundant distribution paths to serve the critical environment. It has a backup for each critical systems component. Components maintenance can be done without shutting down the system. It implements dual power sources and redundant cooling. All IT equipment must have dual power supplies attached to different UPS units, such that a UPS unit can be taken off-line without crashing servers or cutting off network connectivity. Redundant cooling systems must also be in place so that if one cooling unit fails, the other one kicks in and continues to cool the room. Tier 3 DCs are not fault tolerant as they may share different components such as utility company feeds and external cooling system components that reside outside the data center.
Tier 3 data centres are the go-to solution for companies who want a guaranteed uptime without competing against elite brands.
Tier 4 Data Center
- Downtime per annum: 26.3 minutes
- Redundancy: Partial cooling and multiple power redundancies
- Uptime per annum: 99.995 %
- Power Outage Protection: 96 hours of protection
- Fault Tolerance: 2N+1
- Zero single points of failure
Tier 4 data centres add fault tolerance to the Tier III topology. When a piece of equipment fails, or there is an interruption in the distribution path, IT operations will not be affected. All of the IT equipment must have a fault-tolerant power design to be compatible. Tier 4 is considered an enterprise-level service and they have double the infrastructure of a Tier 3 facility. They ensure the safety of your business regardless of any mechanical failures. It implements backup systems for cooling, power, data storage, and network links. The site infrastructure is able to sustain at least one worst-case unplanned failure or event with no critical load impact.