What Is Fault Tolerance?

Imagine this: You run an online retail business, and it’s the busiest shopping day of the year. Suddenly, your onsite server goes down, and customers can no longer access your website. Instead of buying from you, they look elsewhere. The experienced downtime is more than just a computer or tech problem. It’s a risk for your business. 

Robust fault tolerance measures are essential to ensure that your company can continue operating, even during unexpected failures. In this guide, we discuss fault tolerance, its importance in modern IT infrastructure, and how to maximize your uptime to stay ahead in today’s competitive business environment. 

Fault tolerance defined

Fault tolerance is the ability of a system to work even when parts fail. Fault-tolerant systems utilize alternative routes, extra equipment, and backups to prevent a complete service outage. If one part, such as a server, goes offline or breaks, traffic is routed elsewhere, just like a detour for road construction. When done right, users won’t even notice there’s been an outage. 

Data centers, cloud platforms, and enterprise networks utilize fault tolerance systems to create failover mechanisms, ensuring workflow continuity and eliminating downtime. This continuous availability makes your network more dependable, which boosts productivity and profit. Fault-tolerant cloud-based systems often have a parallel high-availability (HA) system in a separate cloud data center. It is redundant and ready to take over for the primary system if a failure occurs. 

Components of fault-tolerant systems

In the world of cloud computing, fault tolerance is critical, which is why fault-tolerant designs are built into many systems. These systems contain a variety of components, including: 

• Redundant hardware: Redundancy involves doubling or tripling essential hardware and systems parts to ensure that the system can keep working even if one part fails. This includes utilizing multiple servers, disks, power supplies, and more.
• Software monitoring tools: Monitoring tools constantly track system health and performance metrics for predictive maintenance through automatic error detection and logging systems. This allows you to fix a problem before it escalates into a failure.
• Failover mechanisms: Failover systems are backup components that take over when the primary system fails. This automation helps your business stay up and running.
• Load balancers: This essential part of a fault-tolerant system distributes traffic and workloads across resources, such as servers. When one server has problems, load balancers transfer traffic to a different server for continuous service.
• Replication systems: Replication and distributed systems are essential for fault tolerance. By ensuring that data is continuously copied across nodes, you can always access an up-to-date copy of your data if one node fails. 

How does fault tolerance work?

Fault tolerance is like a safety net. Each component supports the system and helps catch potential failures. Fault-tolerant systems proactively use redundancy, replication, failover, and HA techniques such as load balancing and clustering to keep operations running when problems arise. These techniques allow systems to monitor performance and availability in order to eliminate downtime. 

Load balancing

Load balancing allows web and/or server traffic to be evenly distributed among resources or servers, ensuring consistent responses for users. When networks experience traffic surges, load balancing helps prevent poor performance, slow response times, and timeouts. Load balancers monitor target resources and divert traffic when a server is offline or overwhelmed.

Redundancy

One way load balancers divert traffic is through redundancy. Through backup hardware and software, fault-tolerant systems can switch traffic to another server or pathway if the primary one goes down. Redundancy allows you to have multiple instances of the same resources on standby. In standby mode, another server is automatically created and activated when the primary server fails.

There are two common types of redundancy:

• Software: With software redundancy, fault-tolerant systems utilize backup applications and programs on different servers and networks. This is like using a map instead of a GPS if you don’t have cellular service.
• Hardware: With hardware redundancy, fault-tolerant systems utilize extra physical devices, including network cables, storage drives, or duplicate servers. This is akin to using a spare tire when your original tire goes flat. 

Redundancy allows you to isolate the defective software or hardware from your system before it causes more significant problems. 

Replication

While load balancing helps a fault-tolerant system distribute traffic during a failure, replication ensures that your data is always available. After a transaction, the data is synchronized and stored across multiple servers, so each server has a duplicate of the data. This syncing and replication ensure that when a failover occurs, there is no impact on the user’s end. 

Failover

Fault-tolerant systems use automated monitoring to analyze and track a system’s performance. When this mechanism flags a problem in your system, it uses failover technology to automatically bring the backup system online. It then utilizes rollback and checkpoints to ensure that this backup is up to date before the primary system goes offline. 

A real-life example of a fault-tolerant system is a mobile phone that uses both Wi-Fi and cellular data to connect to the internet. The primary system is the Wi-Fi connection, and the backup is the cellular network. If your Wi-Fi goes out, your phone will automatically switch to the cellular network without noticeable interruption. 

Benefits of a fault-tolerant system

In many industries, such as healthcare, finance, aerospace, or cloud-based services, the importance of fault tolerance cannot be overstated, as full-blown system failures can have devastating consequences. Designing systems with fault tolerance allows organizations across industries to enjoy benefits including reliability, continuity, and high availability of their critical operations.

Other benefits of a fault-tolerant system include: 

• Minimized downtime: Automated fault detection and recovery systems ensure that your system can use backup resources to continue functioning even when components fail. This helps organizations maintain productivity when their network goes down. The system will bring your backup online so employees can still access the database.
• Improved user experience: Fault-tolerant systems reduce disruptions for end users or customers by transferring traffic to a new server if the first one fails or is overwhelmed. In the e-commerce industry, this rerouting ensures that customers can still access your site during peak shopping times, such as Black Friday or Cyber Monday.
• Enhanced data protection: Through replication, fault-tolerant systems can eliminate the risk of data loss or corruption. This is essential for regulated industries such as healthcare. By storing sensitive information in backup servers, healthcare facilities can maintain Health Insurance Portability and Accountability Act (HIPAA) compliance, even in the event of hardware failures.
• Business continuity: Fault tolerance eliminates single points of failure and ensures that mission-critical systems remain operational during outages. For the aviation industry, fault-tolerant systems make sure airplane communication and navigation systems stay online, even if one computer fails.
• Reduced maintenance risk: Fault tolerance enables maintenance and updates without causing downtime. You can perform software updates or hardware changes with a lower risk of disrupting service. For manufacturing systems, fault-tolerant systems enable predictive maintenance. By flagging a malfunctioning component, you can reroute manufacturing operations to backup machines while fixing the main one. 

Factors to consider in fault tolerance

Despite the benefits of fault tolerance, there are obstacles and constraints you need to consider before you can implement fault-tolerant systems. 

Cost

Fault-tolerant systems require significant up-front costs. Fault detection monitoring, redundancy, and backup systems need extra software, infrastructure, and hardware. You may also need to hire a dedicated team to manage and monitor your fault-tolerant system. Even if you use a third-party provider, you’ll pay regular fees to utilize its cloud-based services. This cost could be a barrier for small businesses with a tight budget or limited staff. 

Complexity

Before implementing a fault-tolerant system, thoroughly examine every variable within your existing system to identify which components may fail and require a backup. The larger your system’s scope, the more complicated it becomes. You need to consider redundancy, error detection and correction systems, and failover procedures. 

Fault tolerance is more difficult in distributed systems that span several data centers. If these data centers are spread out across geographical regions, network latency and synchronization can affect failover mechanisms. Your fault-tolerant design needs to consider these factors. 

Scalability 

What works in a small-scale setting may not remain effective as your business grows. As your user base increases, your system must accommodate rising load levels, meaning you need more infrastructure and servers. The more components and relationships your system has, the harder it is to achieve fault tolerance. 

Recovery time objectives and recovery point objectives

Before implementing a fault-tolerant system, consider your organizational recovery time objectives (RTOs) and recovery point objectives (RPOs). Ask yourself these two questions:

• How quickly do I need my system to get back up and running after a failure?
• How current must my backup data be to meet compliance regulations and ensure productivity? 

If you need your system to always be online, invest in fault-tolerance mechanisms such as redundant hardware and software, load balancers, and failover techniques. If you need the most up-to-date data, invest in systems that frequently back up data through replication. 

Compliance and industry standards 

Fault tolerance is essential for meeting compliance and industry standards, especially in the telecommunications, finance, aerospace, and healthcare sectors. To maintain compliance, you often need fault-tolerant systems that eliminate downtime and ensure continuous functionality and data integrity. You must also invest in cybersecurity measures such as encryption, access controls, and multifactor authentication. 

Ensure maximum uptime with fault-tolerant solutions that provide HA and disaster recovery for PostgreSQL deployments 

Don’t let database failures disrupt your business. PostgreSQL solutions from EnterpriseDB (EDB) provide the reliability and performance your enterprise needs with our HA offerings. These are flexible and scalable, allowing you to meet your application requirements with single, active, and multi-region options. 

When paired with your fault-management system, our high-availability platform eliminates downtime through our globally distributed cloud with 99.999% uptime. Our offerings simplify regulatory compliance through built-in security measures, such as encryption and multifactor authentication. Additionally, our easy-to-use interface makes it simple to create access controls to prevent unauthorized access. Speak with an expert today to learn how EDB can help you build a resilient, always-on database infrastructure.