Introduction to vertical and horizontal scaling concepts

When you deploy a given EC2 instance in your VPC, you need to choose an instance type and one or more associated Elastic Block Store (EBS) (or instance store) volumes of specific sizes. Your EC2 instance will always need one root volume and one or more data volumes based on your application requirements.

However, from time to time, you may need to upgrade your original configuration— perhaps you need more memory or more central processing units (CPUs) to cope with the load on your server. You may be running out of storage space and therefore need to increase the amount of storage on your EBS volumes. When upgrading to an instance of a higher specification, we call this vertical scaling. To perform most upgrades this way, you generally need to stop processing application requests, and most of the time, you may first need to shut the EC2 instance down.

The actual upgrade can take anything from a few minutes to a few...