Redundancy and Failover System Design Example

This project demonstrates how to mitigate the Single Point of Failure (SPOF) in system design by implementing redundancy and failover mechanisms. The project involves creating a simple load-balancing mechanism with multiple instances of a service to ensure that if one instance fails, another one takes over, keeping the system operational.

Problem Overview: Single Point of Failure

A Single Point of Failure (SPOF) is any individual component in a system that, if it fails, causes the entire system to stop functioning. This is a major issue in high-availability systems like web applications, databases, or distributed systems, where downtime can result in significant data loss, service interruptions, or financial loss.

Solution: Redundancy and Failover

To prevent SPOF, systems implement redundancy and failover strategies:

• Redundancy: Creating duplicate instances of critical system components (e.g., servers, databases, network components).
• Failover: Automatically switching from a failed instance to a healthy one to maintain service continuity.

This project demonstrates how to build a simple system where multiple services run behind a load balancer, with automatic failover in case of failure.

Project Features

• Load Balancer: Directs traffic to multiple service instances.
• Health Check: Continuously monitors the health of each service instance.
• Failover: Automatically reroutes traffic to healthy instances if one fails.
• Redundancy: Multiple service instances ensure that there is no single point of failure.
• Zero Downtime: Ensures service availability even during server failures.

Project Structure

redundancy-failover/
│
├── src/
│   ├── loadBalancer.js          # Load balancer logic with health checks
│   ├── serviceInstance.js       # Simulates multiple service instances
│   └── healthChecker.js         # Monitors service instance health
│
├── package.json                 # Project dependencies and metadata
└── README.md                    # Documentation

Requirements

• Node.js (v14 or later)
• npm or yarn for package management

Setup and Installation

1. Clone this repository:

   git clone https://github.com/yourusername/redundancy-failover.git
   cd redundancy-failover

2. Install the required dependencies:

   npm install 

3. Start the application:

   node server.js