Data Center Redundancy Explained


Today’s businesses are more reliant on technology than ever before. And with the capabilities of technology growing by the day, we can expect the importance of tech-driven processes to skyrocket over the coming years.

This is invariably welcome news for consumers, who continue to see improvements in customer experiences as a result of such advances. Businesses too are reaping the benefits of smarter, more automated ways of working.

However, there is a definite downside to our increasing reliance on technology – and that becomes crystal clear when unexpected downtime rears its ugly head.

Downtime can now derail companies completely, taking them offline and stopping them from serving their customers at all. It has the potential to sever communication channels, delay shipping and ruin reputations that businesses have been building on for years.

Competitive global marketplaces require businesses to provide a standout service that never disappoints, which is why downtime is such a threat.

Many companies are now making 100% uptime their goal. To achieve it, businesses often require the help of third party data centers, capable of providing the type of resilient environment that they need to stop downtime wrecking their progress.

The risk tolerance of different businesses can vary quite considerably, but if there’s one thing all teams need to understand it’s how critical servers are supported, and how chosen data centers protect a company’s architecture to keep it online no matter what.

What is data center redundancy? 

Redundancy is something that can be achieved in a number of different ways, which is why it can be tricky to make the best decision for your business’s specific requirements.

Put simply, data center redundancy is a number of systems by which IT systems can be protected. Typically, this involves the duplication of components, providing backup options which can be used in the event of issues such as power interruptions, failures in equipment or breakages that happen with little to no warning.

Power redundancy, for example, refers to the practice of protecting IT systems from the impact of a sudden power cut – and keeping impacted businesses online so that their customers don’t know anything about it.

Data center redundancy tiers

Redundancy is key to understanding how reliable a data center is and how well it performs. However, it can be delivered in a number of ways, so it’s sometimes tricky to compare the redundancy of data centers, which might operate quite differently.

If in doubt, refer to the Uptime Institute’s tier rankings. Renowned as a standard bearer of performance in digital infrastructure, the Uptime Institute certifies data centers according to its Tier Classification System. There are four distinct tiers: Tier 1, Tier 2, Tier 3 and Tier 4.

Each tier of the Uptime Institute’s classification system is very specific in the requirements that must be met in order to achieve this ranking. Data centers must have set capabilities and minimum service levels. Factors such as staff expertise, customer support and maintenance protocols are also taken into account.

Take a look at the four tiers and what they mean in terms of guaranteed uptime and expected downtime per year.

  • Tier 1 Uptime: 99. 671% or less than 28.8 hours of downtime per year
  • Tier 2 Uptime: 99.741% or less than 22 hours of downtime per year
  • Tier 3 Uptime: 99.982% or less than 1.6 hours of downtime per year
  • Tier 4 Uptime: 99.995% or less than 26.3 minutes of downtime per year

Data center redundancy best practices

Data center redundancy provides protection to all components, to keep businesses online as much as possible. However, it’s always worth focusing on the protection of the most vital components first.

Power supplies should be prioritized and duplicated, particularly given the fact that the number of natural disasters and extreme weather events that we’re experiencing is now on the rise. Data centers need uninterruptible power supplies to function. Without this, the duplication of other components would be futile – no matter how many copies were made.

We also recommend that the following systems are duplicated:

  1. Backup generators
  2. Cooling systems
  3. Individual servers and their associated data

Third-party support can be used with redundant data centers, to eliminate further risks and provide added protection for critical processes.

Geo-redundancy is another design that’s well worth considering. This design gives added protection from natural disasters and weather events, meaning that if a hurricane, flood or huge storm did take a data center offline, the company would theoretically be able to continue to serve its customers, without interruption. This is particularly beneficial to global businesses, whose customers in one region might be completely unaware of the extreme weather battering a data center on another continent.

Data center redundancy design

Redundancy can be designed in many different ways. It’s built into the infrastructure of data centers, with critical components such as cooling systems, backup generators and UPS systems all being duplicated in the first instance.

Data centers have different levels of redundancy, and this gives us a glimpse into how well they might avoid unexpected downtime. For many businesses, 100% uptime is essential, however fully redundant options tend to be more expensive, and might not really be necessary for some companies.

Redundancy is now achieved through many different configurations, giving a range of options that businesses can choose from to balance their focus on uptime without overstretching their budgets. Progressive levels of security can be purchased according to the specific requirements of companies, and their own risk tolerance.

Data center redundancy levels

Data centers have developed a range of redundancy levels to meet the diverse needs of businesses. The levels are:

  • N
  • N+1
  • N+2
  • 2N
  • 3N/2

The “N” in these levels refers to the minimum capacity needed to power or cool a data center with a full load. For example, a data center requiring a total of four UPS units to operate would have an N of four. The N rating of each data center therefore gives us a good understanding of its power and performance requirements.

Bear in mind that data centers can use a number of different redundancy models, so it’s possible to have a UPS of 2N, with a cooling system level of N+1. Critical parts of the power flow processes therefore would need to be 2N, to avoid having a single point of failure in the system.

N+1 redundancy increases the number of components. This simply means that if your business needed five UPS units, an N+1 plan would mean you had six. So, you’ve got an extra unit at your disposal if one should fail. It applies to all components, from servers and storage hardware to HVAC systems and generators.

2N redundancy is far more than the next step up from N+1. With 2N, you would have double the number of units needed. So, if you had four UPS units, 2N would provide eight. This option also provides separate distribution systems for a seamless switch when needed.

3N/2 is another redundancy option, which incorporates a buffer against faults in a more cost-effective way. Additional capacity is based on the load of the system here, so you’d get almost the same reliability as 2N, but the operating costs are more comparable with that of N+1 options. There are additional load management challenges to consider with 3N/2, however.

Data center redundancy pricing

Redundancy doesn’t come cheap – but it often pales in comparison to the potential cost implications of unexpected downtime.

To protect profits and keep customers singing their praises, businesses need to carefully weigh up what downtime might mean for their processes, considering how budgets can be best spent to protect the business as a whole.

Businesses need to find the perfect middle ground between reliability and cost to find the redundant architecture that best suits their requirements. And this isn’t always easy.

We recommend mapping your needs to an appropriate redundancy model, checking that your chosen data center offers the right level of protection and uptime guarantees for your business needs – and your budget.

If you’re unsure about what your company might need, or you have further questions about fault tolerance and redundancy, don’t hesitate to get in touch with our team.