What is high availability in AWS?

AWS stands for Amazon Web Services. AWS is one, most popular and ever-evolving cloud computing platform developed by Amazon. This cloud computing platform not only allows the computation but also offers many other services in order to make it much easier for a developer to develop an application and also allows users to focus primarily on the business logic as it automatically manages most of the application components such as Operating system, hardware needed, memory required, etc with “pay as you go” pricing scheme.

High availability of an application means how fast the application responds to the server or to the customer. Here availability means the application is available for the customer. Higher availability results in lower latency. So today in this article we will discuss various strategies to attain High availability on an application created on AWS.

Region:

A region is a separate, self-contained geographic area where all the resources needed for an application are contained. AWS has regions spread in the whole world. These regions are further divided into an availability zone. The availability zone is the different and separate isolated spaces within a region containing all the resources. So when you create an application, An availability zone from a specific region is selected for launching that application. Choosing the right region is an important factor.

Suppose your customers are located in Rio De Janerio and you choose the USA region instead of the Sao Paulo region. Although the application will work because of the distance, an extra bit of lag will occur. On the other hand with the Sao Paulo region, this lag can be removed and the application will be much more available.

Although these regions are increasing rapidly.

Availability Zone:

As mentioned above, regions are geographic areas and are located in big cities such as Sydney, London, etc. These regions contain many availability zones which might be a distance apart but within the same region. These availability zones also contribute to achieving the high availability of applications.

So to compute or to develop an application, the developer must launch an Elastic Compute Cloud (EC2) instance. These EC2 instances are launched in a specific availability zone of a specific region but suppose what happens to the application if due to some reason that specific availability zone is not available. Although AWS ensures no data loss but your application will not be available. So in order to tackle this situation, and to increase availability, 1 must launch 2 separate EC2 instances in 2 different availability zones.

EC2 Auto Scaling:

Elastic Cloud Compute Auto Scaling is one of the many services offered by AWS. EC2 Autoscaling contributes to achieving higher availability by automatically removing or adding instances.

The other two:  Finding a suitable region and more than 1 instance approaches the primary level approaches and doesn’t help much but when it comes to heavy traffic, EC2 Auto Scaling finds its application. To understand better suppose you have chosen the right region and are using different EC2 instances within the same region but different availability zones. But suddenly the traffic of your application increases so much so that the available instance is unable to handle the traffic. Then the EC2 auto-scaling will add new instances to divide the traffic. This will return the availability as more users can use the application at the same time.