AWS — High Availability and scalability

Scalability:

Scalability: It means that the application/system handle greater loads by adapting.

There are two types of scalability:

1. Verticle scalability
2. Horizontal scalability(= elasticity)

Vertical Scalability:

1. It means increasing the size of the instance.
2. For example, your application runs on a t2.micro
3. Scaling the application vertically means running it on t2.large
4. Vertically scalability is very common for non distributed systems such as databases.
5. RDS, ElastiCache are services that can scale vertically.

Horizontal Scalability:

1. It means increasing the number of instances.
2. It implies distributed system such as a web application.

High Availability

1. It usually goes hand in hand with horizontal scaling.
2. It means running your application in at least 2 data centres (==availability zones)
3. The goal of high availability is to survive a data centre loss.
4. It can be passive or active.

This article content is taken from Stephane Maarek(Udemy Instructor).

Happy to Help :)