Scalability refers to the ability of a system to handle an increased load by adding resources.
Scale up vs Scale out
Scaling up means adding more power to existing machines while scaling out means adding more machines.
To remember this, think of scaling up as “vertical” (upwards) increase in power. Scaling out can be considered as “horizontal” (expanding) increase in machines.
What then does scaling in mean?
- It’s the opposite of scaling out. It means decreasing the number of EC2 instances.