Server Redundancy: Types, Benefits & Design

Updated on Jun 1, 2022

FS Rack Servers

When data is all-important to business operations, you need server redundancy when trouble strikes. What happens if you lose access to your data and applications? If you don’t have server redundancy, your business may suffer disastrous losses. This article will cover all you need to know about server redundancy: its features, benefits, different types, and how to create server redundancy.

What is Server Redundancy?

Server redundancy refers to a measure of setting up backup servers to support a primary server. For example, a site hosted on a single network server without any backups is not redundant.

A redundant or backup server is essentially a mirror image of your primary server. This means it has the same storage, applications and compute capacity under the very same configurations. If your primary server goes down for any reason, your redundant server can act as the main operating system.

server redundancy

Having a redundant server is like having a spare tire for your network. During downtimes, you can just swap the flat tire for the spare one and continue toward your goal instead of being stuck on the side of the road. Your business will still be able to function in unexpected events.

One thing to notice is that some redundant servers are not always online, and they are not used as "live" servers until they are needed. But they still have network connectivity ready to go and can receive power. During extreme traffic or downtimes, redundant servers are often used to share the workload or pick the network back up.

Types of Redundant Servers

Server redundancy types refer to different redundant servers that can be deployed on a site. Generally, there are three different types of redundant servers that businesses can use to protect their data and applications.

Domain, front-end, and validation servers

These servers are used for load balancing to ensure users can always access a service. For example, if the primary server goes down or gets too congested, the redundant server can validate user access to the domain for better load balancing.

Replicated servers

A replicated backup server is an exact replica of your primary server. Even if your primary servers crash entirely in the event of a disaster, replicated servers can be activated to get the system back to full computing power quickly. But implementing complete proxy servers can be expensive.

Disaster recovery servers

Disaster recovery servers are semi-hot spares built specifically to hold backup information. When disasters strike, they can restore data and processing ability to your primary servers, like a jumpstart for your car.

Benefits of Server Redundancy

No business wants to be stuck with a single failed server. Server redundancy offers a number of benefits to help businesses evolve.

Reduce Downtime

Downtime can be quite expensive. Redundant servers can access critical data and maintain normal operations whenever disaster strikes and a primary server goes offline, which greatly reduces downtime and enables maximum uptime.

If your primary server needs to be shut down for maintenance, a backup server can always fill in. Your system can still function as usual using redundant servers while the IT department works to resolve the issue.

Improve Resilience

By providing additional resources that can be deployed in the event of disasters and failure, server redundancy also addresses resilience.

Many redundant servers come with real-time system monitoring features. They can constantly scan your primary server cluster for problems and possible failure. With real-time monitoring, your IT team can prevent potential failures before they happen and maintain the health of your servers.

Enhance Performance

As your business grows, the capacity of original servers may become too small for peak time usage. A performance-oriented deployment of redundant servers can help solve the problem.

Multiple redundant servers can be combined to form a server cluster in which two or more servers share the same IP address. They can function as a single server on the network. As the company grows, the IT team can choose to use the original server and the backup server simultaneously.

The redundant cluster can provide both enhanced performance as well as cost-effective redundancy by adding additional servers to the cluster.

How to Create Server Redundancy

The following are some aspects to consider if you plan to create server redundancy in your current architecture.

A New Network Infrastructure

At the fundamental level, creating server redundancy means constructing a new network infrastructure that houses identical information of your primary server. Generally, to create server redundancy, at least you will have one primary server and an identical backup server.

However, simply having the backup server is not the same as having it ready. If you purchase a server and keep it in the shipping box in the server room, you can say you have achieved server redundancy, but it is not a resilient system. Because it will take time to deploy that redundant server. You will have to make sure your redundant server can take up the slack once the primary server fails, and the process should be as prompt as possible to reduce delays.

Other Redundant Parts

In addition to a redundant server, other parts of your infrastructure should also be duplicated to ensure maximum uptime in the event of disasters.


Backups can be deployed to create copies of your data and store it away separately. This allows for quick retrieval of the backup data in case of data loss in the event of a disaster. Failure to do this may result in permanent data loss, causing your business to face negative repercussions.

Disk drives

Redundant disk drives improve performance by increasing the number of hard drives used for saving and accessing data. If a disk drive in a primary server fails, another drive can immediately fill in so that a server can keep running when there is a single disk failure.

Power supplies

With redundant power supplies deployed on critical servers, if the main power supply goes down, the spares will still have the capacity to maintain the normal operation of your servers.

Internet connectivity

Uninterrupted internet connectivity should be available so that your primary server can have a connection to the internet at all times. It is necessary to have a line from a different telecoms company. If one line fails or needs to go down for maintenance, traffic can shift onto the backup line.

Server Failover

To take your server redundancy to the next level, many businesses also implement a failover monitoring server that scans the primary servers for potential issues. If it detects an error or any signs of failure, it will automatically reroute network traffic to redundant servers by updating the DNS records. Here the server failover refers to automatic failover.

In automatic failover, the shift to a redundant server happens automatically. There is usually no downtime associated with a switch to a secondary server. The switchover is a similar process, only the shift to the secondary server happens manually, creating a short period of downtime. Usually, automatic failover has high resilience but costs more, while switchover incurs minimal operating costs but has poor resilience.

Configuring either failover creates server redundancy that increases uptime and prevents outages, but businesses need to choose between automatic failover and switchover. Before making a decision, you have to balance the benefits they offer with the level of risk and the substantial costs associated with them.

Server redundancy helps your business to evolve with high resilience and performance. That said, you still need to balance the redundant server deployment with priorities of your business and potential risks and costs associated.

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