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Redundancy

Redundancy is the key to achieving high availability in IT infrastructure, ensuring systems stay online even when individual components fail. This content covers how to build resilience across every layer of an environment, from hardware and networking to power, cooling, and data.

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About this video

Even the most carefully designed infrastructure, built with top-tier servers, databases, and network connections, is still vulnerable to failure if redundancy is not part of the architecture. No internet service provider or cloud platform can guarantee 100% uptime, and unpredictable events like natural disasters or hardware faults make some level of failure unavoidable. Redundancy is the primary strategy for getting as close to continuous availability as possible, and it is foundational to any serious high availability design. In practice, redundancy means deploying multiple instances of every critical component so that when one fails, another takes over without interrupting service. This applies to servers, database systems, and network connections between users and the infrastructure serving them. But redundancy does not stop at hardware. A comprehensive approach extends to geographic separation of facilities, diverse power sources, cooling systems, networking paths, software services, and data replication, covering every layer of the stack that contributes to delivering a reliable service.

What you'll learn

What's covered

Redundancy in IT Infrastructure

Key terms

Redundancy
The duplication of critical components or systems to increase reliability and availability.
Failover
The automatic switching to a redundant system or component when the primary one fails.
Availability
The assurance that systems and data are accessible and operational when needed by authorized users.
Load Balancer
A device or software that distributes incoming network traffic across multiple servers to ensure availability and performance.
High Availability
HA
High Availability describes systems designed to operate continuously with minimal downtime, achieved through redundancy, failover clustering, and load balancing to meet the Availability pillar of the CIA triad.
Disaster Recovery
DR
The process and procedures for recovering IT systems and data following a disruptive event.

Topics

Redundancy High Availability Fault Tolerance Infrastructure Resilience Power Redundancy Data Redundancy Network Redundancy

Transcript

We could go all out in choosing the right location, choosing the right equipment, choosing the right software, and setting it all up in the right way, but if we don't have redundancy, we're probably going to go down, and maybe even go down often.

The fact is that there are problems out there. There are still natural disasters that happen. There's still no internet service provider that can give us 100% uptime. There are service providers from a cloud perspective that can't give us 100% uptime. We just can't achieve this 100%. But one of the ways that we can get as close as possible is creating redundancy.

Why the Best Equipment Is Not Enough

Let's say we have a web application that we want to have highly available. We're trying to achieve high availability, HA. What we do is we go out and buy the best server and the best database server and the best internet connection, and so we have everything, the best of the best. But the thing is, something is still bound to fail.

We could buy all of the best servers and set them up, but if there's no redundancy within there, as soon as that goes down the end user is going to go offline. And something along the way is bound to fail.

Building in Redundancy

So that's where we set up redundancy. We have multiple servers that are running, so if one of them goes offline, then the other ones kick in. We have multiple database servers, so if one goes offline, the other one kicks in. We've got multiple connections between our customer and us, so that if one of them goes offline, we're still up and running.

So where do we want to see this redundancy?

  • With location, we want to actually have things geographically separated.
  • With power, we want to have multiple power sources.
  • With cooling.
  • With networking.
  • With hardware.
  • With software and services.
  • With data.

So essentially any aspect that we can think of within our organization, within our infrastructure, within our services, whatever is delivering those services, we want redundancy with those.

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