Failover: What It Is and Its Importance in Business Continuity

Have you ever thought about what a disaster might look like to your business without the ability to failover? Ransomware, hurricanes, floods, hardware failure, file corruption, human error and dozens of other disasters can bring business productivity to a standstill if your organization is not equipped to handle an outage situation.

Does your business have a disaster recovery (DR) plan? How quickly can your company restore applications and business services and get back to business as usual in the event of a major failure? Does your organization leverage modern business continuity tools with the capability to failover in accordance with business objectives (such as Recovery Time Objective or RTO) to maintain operations when your primary production site goes down?

In a fast-paced, always-on business landscape with no room for downtime, even a brief interruption could result in lost productivity, opportunities, customers and revenue. Therefore, IT professionals and business owners must ask themselves the above questions to ensure their mission-critical business operations remain unhindered regardless of the circumstances. Read on to learn what failover is and how it helps mitigate downtime and ensure business continuity.

What is failover?

Failover is the process of switching critical workloads, systems and applications to a standby or secondary site when the primary site is down or unavailable for any reason. Although failover is essential to backup and disaster recovery, its application is also vital during planned downtime for system upgrades, repairs and testing.

By providing both system- and network-level redundancy, failover ensures your business operations can continue with little or no downtime, even during a disaster or scheduled maintenance. Today, many solutions offer automation around the failover process. When the recovery site detects a system failure or an outage, it will trigger an automated failover, switching operations from the primary site to the secondary site. However, some systems, known as automated with manual approval configuration, alert the data center or technician instead to manually switch operations to a standby computer or server.

Why is failover important?

The main goal of failover is to reduce or prevent complete system failure, thereby achieving more fault tolerance. Fault tolerance is the capability to deliver uninterrupted service despite component failure, making systems resilient against single points of failure. Failover is vital for mission-critical systems that must always be available. A failover operation ensures employees can work without disruption, and files and systems are readily available and accessible during planned and unplanned outages. The ability to failover is essential, especially if your business has stringent uptime requirements.

What is the failover process?

A failover operation can be applied to different components of a system, database, network and more. To better understand how a failover process works, let’s take the example of your office environment where the computers are connected to a server(s) and a network or the internet. In the event of a disaster or an unplanned outage, if the server goes offline or the network is down, you won’t be able to access your files and folders or execute other business operations without failing over to a secondary system. However, if your company has a failover solution in place, it will automatically switch workloads to a reliable backup system, ensuring your files and folders are readily accessible. In failover, when your primary server becomes unavailable, the secondary server instantly takes over the functions, which minimizes downtime and ensures high availability (HA).

What is failover clustering?

In computing, a failover cluster or clustering is a group of computer servers that work in tandem to make applications and services more fault tolerant. Failover clustering is a means to achieve continuous availability (CA) or HA. Suppose one server, also known as a node in a cluster, fails, another node in the cluster immediately assumes the functions or takes over the failed server’s workload, thereby preventing downtime. A failover cluster may consist of two or more physical servers, virtual machines or both.

What are the two configurations of a failover system?

Active-active and active-passive are the two most common HA configurations. Although both configurations improve the reliability and accessibility of applications and services, each technique achieves failover differently.


At least two nodes execute the same task simultaneously in an active-active HA configuration. This ensures the workload is evenly distributed and balanced across all the nodes, which prevents overloading on any one node. The active-active cluster improves throughput and response times since more nodes are available. The configurations and settings of each node should be the same to achieve redundancy and ensure the HA cluster runs seamlessly.  


Like in an active-active cluster, the active-passive or active-standby HA configuration also consists of at least two nodes. However, as the name suggests, not all the nodes are active. For easy understanding, let’s consider a two-node setup where one node is always active, and the other is on passive or standby mode. Here, the passive node is the failover server, ready to take over operations if the active node goes down. Similar to the active-active cluster, both nodes must have the same settings for a smooth failover process.

What is a failover test?

Failover testing is a method used for validating a system’s failover capability. It assesses if a system can allocate adequate resources for recovery following a system or server failure. This helps verify whether the system can rapidly switch operations to standby systems and accommodate additional resources necessary for a successful failover in the event of a failure or sudden termination caused by natural or man-made disasters. Failover and recovery testing help determine if the system can handle and power an extra CPU or multiple servers once its performance threshold is reached, which typically occurs during critical failures. These tests help to understand the crucial relationship between security, resilience and failover testing.

The term failover is often associated with or confused with other disaster-recovery-related concepts. Let’s take a closer look at them to understand the concepts better.


Failback is the process of returning production from a secondary or backup site to the original location after a disaster or planned outage. Once your primary site is up and running and all issues associated with the outage or disaster are resolved, you can switch workloads back to the primary production site. In a failback operation, only the changed data is returned to the original source.

Disaster recovery

Disaster recovery is the ability of an organization to resume business operations in the aftermath of a disaster. A disaster recovery plan consists of several processes and techniques to keep systems running with little or no downtime during and after a disaster. It includes a backup and recovery plan to recover lost data, restore it and get everything back on track to mitigate the negative impacts of a disaster.

Load balancing

Load balancing is the process of evenly distributing workloads across a set of resources or multiple servers instead of transferring operations to a single server. This method prevents overloading a single server and improves request response time. Load balancers use algorithms, such as round-robin, to distribute workloads cyclically.


Redundancy, in simple terms, is the practice of storing data or applications in two or more places. Since redundancy duplicates or backs up data, you can immediately access the information if lost, damaged or compromised. Redundancy improves reliability, uptime and the availability of data and/or applications by storing multiple copies of critical components.


Data replication creates multiple copies of data and stores them in different locations for backup, fault tolerance and improved accessibility. This process enhances the resilience and reliability of systems by storing data at multiple sites across the network. In case of a technical glitch due to malware, software errors, hardware failure or other disruption, you can still access data from a different site.


A switchover, also known as a graceful switchover or role switch, is used for planned outages where the secondary site assumes the role of the primary site. The processes of failover and switchover are similar. However, in failover, the shift from a primary site to a standby site occurs automatically, while the operation is manual in switchover. Due to this reason, users may experience a short period of downtime.

What are the benefits of failover?

Having a failover solution is crucial for the survival of your business and offers multiple benefits. Here is a list of key benefits of deploying a robust failover solution:

  • Ensures business continuity: Failover ensures your business remains as usual during a disaster or when critical components go offline. Your clients won’t even know that you suffered a technical failure.
  • Improves uptime: A failover process minimizes downtime by rapidly switching to a redundant standby system when the primary system becomes unavailable so you can continue working without interruption.
  • Saves money: Implementing a failover solution can save you money by minimizing the costs associated with downtime, including lost revenue, productivity, opportunities and brand reputation.

What are the disadvantages of failover?

Failover can be highly beneficial for your organization when done right. That said, like every other technology solution and process, failover has its share of challenges you must know about. Here are some of the drawbacks associated with failover:

Expensive: Apart from the hardware and software costs, setting up, managing and monitoring failover systems can come with a hefty price tag. To ensure failover operations run automatically and smoothly, you will require high-bandwidth systems with synchronous data transmission capabilities, which require substantial capital investment.

May require third-party expertise: Like primary systems, failover systems must be maintained, tested and verified to ensure they work seamlessly. If your company needs more expertise to deploy and manage failover systems, you must rely on third-party experts, which can also increase costs significantly.  

Rely on orchestrated failover with Unitrends

Failover is a disaster recovery mechanism to minimize downtime and mitigate the negative impacts of a disaster or an outage on business operations and customers.

Whether your business runs on on-premises data centers, public cloud, private cloud or both, Unitrends provides a reliable way to keep your business up and running in the face of disasters.

If on-premises data centers power your business, use Data Copy Access (DCA) to orchestrate your DR runbook to execute at a pre-defined target in a failover event. DCA is a job type available with Unitrends Recovery Series appliances and Unitrends Backup virtual appliances. The DCA job offers runbook orchestration to perform recovery testing, spin up instant lab environments and failover production workloads to a secondary target. You can customize your runbook with regard to boot orders, machine reconfiguration, networking and more for both simple environments and complex N-tier applications.

For organizations lacking the resources or expertise to manage a colocation, Unitrends DRaaS can help protect critical workloads from surging cyberthreats and unplanned outages at a cost significantly lower than building and maintaining your own DR site. Unitrends DRaaS, our white glove service, enables you to rapidly spin up a virtualized version of your critical systems and applications in the secure Unitrends cloud for rapid and effortless recovery — all with minimal investment of your time, effort and money.

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