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What Is N+1 Redundancy in Data Centers? 

by Tim

Data centers function on the assumption of reliability. Businesses rely on data centers to store and process their critical data. This means that downtime, no matter how short, can be disastrous. 

It is also why data centers use various redundancy strategies to counter the effect of downtime and minimize the risk altogether. N+1 redundancy is a popular way to reduce downtime because it is cost-effective. 

Understanding the concept of N+1 redundancy in data centers will help you grasp why it is so vital to the data center setup. Keep reading to discover the core principles of N+1 redundancy, how it works for data centers, and its numerous advantages. 

What Does the N in N+1 Mean?

In the context of N+1 redundancy, the N is much more than just a letter. N represents the minimum number of critical components required in a data center to keep it functional. These components include the following: 

  • Power supply units (UPS): UPS devices ensure data center equipment gets a continuous power flow. It does this by providing backup power should there be a surge or outage. 
  • Generators: Extended power grid failures happen all the time due to storms and other factors. When this happens, generators kick in to keep data centers powered up. 
  • Cooling units: Data centers must stay cool. If they get too hot, the equipment can fail. Redundant cooling units prevent overheating and subsequent system failures. 
  • Network switches: A network switch sends data traffic within a data center and outside of it. Redundant switches allow for uninterrupted communication should one unit malfunction or fail. 
  • Storage arrays: Data storage systems also benefit from N+1 redundancy. Additional storage units can act as backups should a primary unit fail. 

What Is the +1 in N+1? 

The +1 refers to the presence of an extra critical component. This component adds one beyond the minimum requirement (N). These extra components are backups if primary units encounter unexpected problems. 

For example, if a data center needs four UPS devices (N) to function at full capacity, an N+1 configuration would include five UPS units. Data centers use the additional UPS as a safety net to ensure uninterrupted power supply. The power supply will remain stable even if one primary UPS unit fails. 

Benefits of N+1 Redundancy

The main benefit of N+1 redundancy is improved uptime. N+1 continues to reduce the risk of downtime caused by equipment failure. This means businesses enjoy uninterrupted service. 

Moreover, N+1 system configurations can overcome the failure of one critical component without losing functionality. Redundancy also allows for planned maintenance and upgrades on individual components without shutting the system down.

Because a backup is in place, technicians can maintain or fix the primary unit without impacting data center performance.

Best of all, N+1 is an affordable option, especially compared to 2N+1 systems. By adding just one component, data centers improve their functionality without running up excessive costs.

Limitations of N+1 Redundancy

Unfortunately, even a system as impressive as N+1 is not infallible. These configurations remain vulnerable to multiple failures. If more than one component fails simultaneously, the data center will inevitably experience downtime.

Also, whenever an extra redundant component is added to an N+1 system, it will consume more power, adding to operational costs. This also means an increased carbon footprint. 

N+1 Vs. Other Options

N+1 is just one of many data center redundancy options. Others include: 

  • N: This refers to a basic configuration with zero redundancy. This is the cheapest option, but there is no protection against component failures. It is also the configuration that will likely experience the most downtime. 
  • N+2: This system includes two extra components beyond N. It provides a higher level of failure tolerance when compared to N+1. This means it can keep the data center operating even if two components fail. This extra protection does come at a higher cost, however. 
  • 2N: This configuration doubles the number of critical components. This setup offers the highest tolerance level during failures, ensuring operation even if half of the components fail. 2N redundancy is also the most expensive data center option. It uses additional hardware and uses far more power than other systems. 
  • 2N+1: This data center configuration combines the best of 2N and N+1. It offers double the number of critical components with one extra unit for more protection during failures. This system can overcome multiple component failures, including failure of the primary system. This option is both the most expensive and resource-intensive redundancy method. 

N+1 Is Practical and Cost-Effective

Despite performing slightly inferior to the more expensive configurations, N+1 redundancy is sufficient and practical for many data centers. By planning for and implementing N+1 redundancy, data centers can ensure reliable operation and uninterrupted service. 

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