Failover

What is a failover?

A failover is a backup operation that switches the primary system to a secondary computer, network, or component when the central system fails or temporarily shuts down. It ensures that the systems continue to operate and provide services during downtime.

Managed domain name system (DNS) providers help organizations manage failover while controlling DNS traffic. It prevents system downtime, helping the company save on costs. System downtime doesn’t imply loss of sales or productivity, but if there are damages related to service level agreements (SLAs), it can cause penalties.

Failovers are a part of a comprehensive risk management strategy and help businesses maintain continuity in unforeseen incidents. 

Many organizations use failover clustering to employ a network of systems and servers to make software applications fault tolerant. They aim to achieve consistent availability. If one server fails, another will take its place and load. This process requires several physical servers and virtual systems.

Types of failover

There are factors like budget constraints, and technical requirements organizations consider before choosing the failover type they would employ. Below are some notable failover types on the market. 

• Active-passive failover: This is the most common failover. Here, the secondary or passive system becomes active only when the primary system is corrupted.
• Active-active failover: The primary and secondary systems work together to handle the workload. If one system or component fails, the other takes over, ensuring efficient resource usage. However, it requires complex load balancing and synchronization.
• Load-balanced failover: Multiple servers run parallelly, and a load balancer distributes their workload. If one component fails, the workload gets distributed among the remaining servers.
• Geographic failover: It deploys backup systems in multiple locations to protect distant sites from failure caused by accidents.
• Database failover: These are designed for databases and involve primary and standby databases. Like other failovers, the secondary or standby database takes over if the primary database fails.
• Cloud-based failover: Uses cloud resources as a failover mechanism. This is common in hybrid environments where cloud services are used as a backup for onsite failure.
• Storage failover: Involves multiple identical storage systems. If the primary storage fails, the other storage ensures data accessibility.
• Application-level failover: Some apps come with inbuilt failover capabilities. If the app fails on one server, it can automatically restart or switch to the second server.
• Network failover: It retains copies of network paths and components. The system will automatically follow the second path if one network path fails.
• Domain name system (DNS) failover: Uses DNS management to redirect traffic to a different server or site if the primary site shows an error or is unavailable.

What happens in a failover?

Failover ensures an effortless transition from a primary to a secondary system in crisis. Here’s what exactly happens. 

• Initial state: The primary system is actively serving requests.
• Trigger: Failure detected in the primary system.
• Failover activation: The secondary system automatically takes over the action.
• Traffic redirect: All the requests are now directed to the secondary system.
• Primary system restoration: Failback occurs when the primary system is fixed, and everything returns to the primary system.
• Monitoring: Ensures stability and readiness to maintain service reliability. 

Failover applications

Different sectors make use of failovers according to their requirements. Below are some common use cases in various industries.

• Financial services: Banks and financial institutions use failovers to ensure the continuous availability of transaction processing systems. These organizations often employ active-active failover mechanisms for high availability.
• Healthcare: Hospitals and healthcare providers use failover to maintain access to electronic health records (EHRs). They employ database replication and virtualization to ensure data integrity and accessibility. Employing failovers here significantly reduces downtime and ensures patient safety and care continuity.
• E-commerce: Online e-commerce businesses use failover to manage website availability, especially during high-traffic events. Generally, load balancers distribute traffic evenly across all the servers, with active-active configurations to handle spikes.
• Telecommunications: They use network failovers to ensure uninterrupted service. They implement multiple components and paths to maintain connectivity even if one node fails.
• Cloud services providers: They have inbuilt failover options for hosted apps and data. These use a combination of geographical failover and virtualization to ensure service continuity across the globe.
• Government and public sector: Emergency management and public safety departments use failovers to keep critical infrastructures running during emergencies and disasters without interruption.

Best practices for effective failover management

Effective failover management is crucial for ensuring business continuity and resilience. Below are some best practices businesses can follow. 

• Test failover systems. Frequent checks and tests can prevent failover malfunctions during an outage. Simulated failover drills help identify and mitigate potential issues in the process.
• Update failover plans. Revisit strategies to implement new technologies, infrastructural changes, and improved objectives. Regular audits and reviewing failover procedures ensure alignment with the current practices and technological changes.
• Train staff. Users should know the failover action plan and their role during an active failover event. Increased awareness helps users understand the importance of staying prepared to execute failover plans effectively.

Learn more about how failovers improve service uptime for businesses.