Availability and Scalability - Overview

Question 1

What does scalability mean in cloud computing?

Answer 1

Scalability means the ability of a system to handle increased load by adapting. It can be either vertical or horizontal.

Question 2

What is vertical scalability?

Answer 2

Vertical scalability involves increasing the size of the instance (e.g., upgrading to a larger EC2 instance type).

Question 3

What is horizontal scalability?

Answer 3

Horizontal scalability involves increasing the number of instances/systems to handle greater load (e.g., adding more EC2 instances).

Question 4

How do vertical and horizontal scalability differ?

Answer 4

Vertical: Increasing the instance size.
Horizontal: Increasing the number of instances.

Question 5

Which type of scalability is most common in distributed systems?

Answer 5

Horizontal scalability is common in distributed systems (e.g., web applications).

Question 6

What does high availability mean?

Answer 6

High availability means running your application in at least two data centers or availability zones to survive a failure in one zone.

Question 7

What is the difference between passive and active high availability?

Answer 7

Passive: Only one system is active, e.g., RDS Multi-AZ.
Active: Multiple systems are active, e.g., horizontal scaling with multiple instances.

Question 8

What are Auto Scaling Groups used for in horizontal scaling?

Answer 8

Auto Scaling Groups automatically increase or decrease the number of instances based on traffic/load.

Question 9

What does scale out and scale in refer to in AWS?

Answer 9

Scale out: Increasing the number of instances.
Scale in: Decreasing the number of instances.

Question 10

How is high availability achieved in EC2?

Answer 10

By running instances across multiple availability zones using load balancers or auto scaling groups with Multi-AZ enabled.