System Design - Load Balancers

A load balancer is being used to distribute load across multiple servers or resources. In this session, I will show you where we need to use a load balancer and type of load balancer as well as the algorithms used to implement a load balancer. 

Why Load Balancers:

When a single server can't handle requests then we need to add multiple servers for handling those requests. A Load Balancers distribute these requests across multiple servers so that a single server doesn't need to handle all requests. A load balancer is also being used to check all the resources or servers. If a server is unavailable then it stops sending requests to that resource or server.

Where load balancer is used:

• User to the webserver (Frontend or Backend)
• Web Server to Internal server (Any other services)
• Internal server or backend to database

Types of Load Balancers:

There are mainly two types of load balancers.

• Hardware Load Balancer: Hardware is being used to distribute loads. It's very expensive.
• Software Load Balancer: It is a hybrid approach and software is being used to distribute loads. HAProxy is popular open-source software.

Algorithms of Load Balancers:

• Round Robin Algorithms.
• Weighted Round Robin Algorithms.
• Least Connections Algorithms.
• Least Response Time Algorithms.
• Source IP or URL Hash Algorithms.