Load Balancer Introduction

In this article, you will be invited to know what is a Load Balancer? Why do we need a Load Balancer? and other information related to Load Balancer.

What is a Load Balancer?

To understand what a Load Balancer is, please consider the illustration of server access by the client below:

From the illustration above, it can be seen that the client accesses the server via a network or internet, then the server responds to requests from the client.

Under normal circumstances, the server can respond to all requests from clients. However, in certain circumstances, especially when there are very many requests from clients, for example hundreds or thousands of clients access the server at the same time, the server will be overwhelmed to handle these requests, so the client cannot or is very slow in accessing the server. This is because the server has limited resources (Memory, Processor, etc.), so that at certain points when the request from the client is very high, the server will experience overload.

Against this problem, one easy way to deal with it is to add a server. With the addition of this server, it is hoped that there will be load sharing between the servers so that the server will not experience overload when requests from clients increase sharply.

In order for the load sharing to run optimally, it requires a device that functions to regulate the distribution of the load to these servers. The device in question is a Load Balancer. While the process of sharing the load on the server is referred to as Load Balancing.

How Load Balancers Work

In simple terms it can be said that the way the Load Balancer works is as follows:

For example, if we have a Load Balancer with three application servers, then all requests from clients go into the Load Balancer, then distributed to existing servers. A simple technique for distributing this request is round robin. Through this technique, the first request will be routed to server 1, the second request will be routed to server 2, the third request will be routed to server 3, the fourth request will be routed back to server 1, and so on. In addition, the Load Balancer will perform a Health Check on each server, where if there is a server that is experiencing problems, the Load Balancer will not send a request to that server, but will be routed to another server that is running normally.

Technically, the Load Balancer is assigned an IP, namely Virtual IP. Called Virtual IP because only this IP is known by the Client. They don’t see the servers (behind the Load Balancer) processing their requests.

All traffic that goes to this Virtual IP is then routed to a collection of servers called the Server Pool. So again, Clients only see Virtual IP (Load Balancer) and they don’t see how Server Pool works.

Another reason to use a Load Balancer

In addition to improving the performance of handling requests from clients, there are several other reasons for using a Load Balancer, including:

1. Minimize Down Time

When one of our servers is down, either due to damage, maintenance, or other causes, the Load Balancer will divert requests from the Client to other servers in our Server Pool. Thus, Down Time can be avoided.

2. High Scalability

Load Balancer makes it easy for us to do scalability by adding servers in the same (existing) Server Pool to lighten the existing load. In addition, the Load Balancer also allows us to add a new Server Pool to handle new applications or applications that are different from the first Server Pool.

Load Balancer Type

Currently there are two types of Load Balancers, namely:

1. Software Load Balancer
Software Load Balancer is a software that is installed and configured on a computer (server) that functions as a Load Balancer. This type of load balancer is cheaper than a hardware load balancer, but its performance is highly dependent on the quality of the computer (server) used.

2. Hardware Load Balancer
Meanwhile, Hardware Load Balancer is a special hardware that is intentionally made and ready to be used as a Load Balancer. This type of Load Balancer is usually more expensive than Software Load Balancer, but is more practical and relatively more reliable.

Thus the article about the introduction of this load balancer, thank you for visiting and hopefully useful.

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