Data Center Infrastructure Redundancy – N, N+1, 2N

The duplication of critical systems provide backup if failure occurs

Life is filled with uncertainty. It’s the same with your IT infrastructure. And the more you have, the more you need to be protected from the downside risks of uncertainty. From powerful summer storms to unexpected utility power outages, it’s impossible to know what could happen to your business, or your data center. Therefore, ensuring that your data center has redundant systems is your IT environment’s best solution when the unexpected happens.

What is redundancy?

Redundancy refers to a system design where a component is duplicated so that in the event of a component failure, IT equipment is not impacted. The main goal of redundancy is to ensure zero downtime.

Redundancy Definitions

Key terms include 2N, N+1, and N. Below is what they mean.


The term “N” simply represents the unit that you wish to duplicate – whether it’s a generator, UPS, or cooling unit.

N equals the amount of capacity required to power, backup or cool a facility at full IT load. A design of N means the facility was designed only to account for the facility at full load and zero redundancy has been added. If the facility is at full load and there is a component failure or required maintenance, mission critical applications would suffer.


If N equals the amount of capacity needed to run the facility, N+1 indicates an additional component added to support a single failure or required maintenance on a component. Design standards typically call for 1 extra unit for every 4 needed. Let’s say you have 8 UPS units, then you should at least have 10 total UPS units.


2N refers to a fully redundant, mirrored system with two independent distribution systems. They are not connected in any way and are not dependent on each other. This means that even if one power source has an interruption or loss of power, the other should still supply power and accommodate full load, thereby eliminating any potential downtime from the loss of one side or leg of the system.

If systems fail and your applications crash unexpectedly, then the impact on your firm’s bottom line, business operations, and customer experience can be severe.

According to an annual survey conducted by the Information Technology Industry Council (ITIC), 98% of organizations say that a single hour of downtime costs over $100,000. Beyond dollar signs, downtime can severely impact your firm’s reputation and also impact the productivity of your workforce when they can’t focus on your core business during and right after the downtime.

It’s nearly impossible to prevent natural disasters, local power grid failures or power outages. Therefore, its critical to be prepared for when – not if – redundancy is needed.

What’s the right redundancy configuration for your business?

There’s no set answer to the redundancy question since it depends on many factors like your IT environment, business goals, and budget. Citadel can discuss with you all your requirements to help you determine the best option for your business. Our team of experts can provide recommendations for your specific deployment.

Contact Citadel today to speak with our experts to get the best solution at the lowest-available prices for your business.

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