High Availability Systems: Definition, Importance and Principles

By Indeed Editorial Team

July 15, 2021

High availability systems are technology systems designed to function correctly for long periods of time. Information technology (IT) professionals establish, test and refine these systems to keep communication and information operating correctly in important situations. If you're pursuing an IT role or working with a large computer network, learning more about these systems could help you develop technical knowledge for your career. In this article, we explain what high availability systems are, why they're important, how they work and how they compare to other technology systems and methods.

Related: How To Choose an IT Career Path

What are high availability systems?

High availability systems are dependable technology systems designed to operate without failure for an extended period. IT professionals create these systems to ensure that the technology works continuously. Typically, in a traditional computer system, there may be power outages or sudden changes in website traffic, which can cause failures. A high availability system is a specialized type of system that works to minimize these potential risks so that the network functions correctly.

Related: 15 Jobs in Information Systems

Why are high availability systems important?

High availability systems are important in many industries because they help ensure systems function correctly for a continuous period. Technology and networks occasionally fail, such as when there's a power outage or a server error. In some industries, it's essential that the network remains functional at all times. For example, in a healthcare setting or an autonomous driving car, the system must function at all times to keep people safe.

In other industries, a high availability system can help keep information safe and secure. These systems can help minimize the chance of an error, and if an unexpected event happens, such as a power outage, they can help minimize the effect it has. For example, businesses and financial centers may use high availability systems to ensure confidential data remains secure in the event of a network error or outage.

Related: Everything You Need To Know About Computer Networking

How does a high availability system work?

A high availability system works by identifying potential errors and working to minimize those risks. There's always some risk of an unforeseen event that could cause a system to fail, but technology professionals try to minimize this as much as possible when designing a high availability system. They aim to achieve a 99.99% accuracy, also called four nines. Some standards prefer five nines accuracy, which means the system functions correctly 99.999% of the time.

Here are the main principles involved in a high availability system:

Identifying single points of failure

A single point of failure is a component within a system that is essential for operation. If this component becomes dysfunctional or has an error, the entire system would fail. When building a high availability system, IT professionals need to keep these components in mind. They can then consider ways to prevent failure in this component, and they may prepare for ways to react quickly in case the system fails.

Building dependable crossovers

In the IT field, a crossover is something that adds redundancy to a system, which is an important benefit in a high availability system. Redundancy means there is a component in place that can perform the same job if another component has an error or becomes disconnected. By building in crossovers, companies can help minimize the risks and ensure information and people stay safe.

For example, if a hospital's communication network, machines and computers operate on one power grid, the power connection is a single point of failure. If there were to be a large storm, there could be a power outage, which would affect the entire building. To prepare for this possibility, the company may add a power generator to ensure the most essential components remain functional. This generator can perform some of the same duties as the original power grid, making it a beneficial and reliable crossover.

Making errors and failures noticeable

When a component in a high availability system experiences an error, this failure must be easy to notice. For example, when one server goes down, a high availability system should identity this immediately. IT professionals may design systems so that the network identifies and corrects failure automatically for individual components. This can help ensure the systems stay functional for a continuous period of time.

Using a cluster structure

A cluster structure is an important part of a high availability system. All essential components should have clusters, which are when multiple computers or servers perform the same function. They also use a load balancer, which can help keep components functioning. This way, if there are big surges in data or customer traffic, the system can balance the amounts between servers. To do this, professionals typically build systems that rely on physical hardware and software structures. This combination can help improve accuracy and reduce potential failures.

Related: Hardware Engineering vs. Software Engineering

High availability vs. disaster recovery

When planning a technology system, there are a few different types of strategies you may use. It's important to learn about these and how they differ to ensure you pick the right system for your needs or your clients' goals.

Disaster recovery is a plan companies may create to prepare for extreme events, such as a regional power loss. A disaster recovery plan typically focuses on large events that cause total system failures. A high available system also plans for failures, but on a smaller level. High availability includes preventative measures too, designed to minimize failure, while a disaster recovery focuses primarily on how to proceed after an event occurs. Depending on the needs of your client or business, you may use a high availability system daily and plan for disaster recovery in case an extreme unforeseen event occurs.

High availability vs. fault tolerance

High availability planning is similar to fault tolerance in many ways, but they require different tools. IT professionals design these systems to increase redundancy to minimize failure in a system. Fault tolerance works solely through hardware, while high availability uses a combination of hardware and software.

To implement fault tolerance in a system, IT professionals use specialized equipment that copies each step of the current system. For example, they duplicate all servers, applications and data to help reduce failure. This system makes it easy to store data safely, but if there is an error on a specific part of the server, it could also duplicate the error, which could cause failure. High availability systems use a variety of strategies and clusters to try to minimize this risk even further.

Related Articles

17 Marketing Strategies (With Examples)