Scalability & High Availability

Scalability #

Scalability means that an application / infrastructure can handle greater loads by adapting.

Two kinds of scalability #

• Vertical Scalability
  • Increasing the size of an instance
  • Very common for non-distributed systems, i.e. Databases
  • Hardware limits apply
• Horizontal Scalability (Elasticity)
  • Increasing the number of instances
  • Implies Distributed Systems
  • Very common for web applications or modern applications
  • Auto Scaling Groups
  • For Horizontal Scaling (increasing the number of instances) we use Auto Scaling Groups and a Load Balancer

High Availability #

• High Availability usually goes hand in hand with horizontal scaling
• High Availability means running application / infrastructure in at least 2 Availability Zones
• Goal of High Availability is to survive a data center loss / disaster

High Availability is achieved by running Auto Scaling Groups (ASG) as well as Load Balancer in multi-AZ mode. #

» References « #

• Elastic Load Balancing
• Auto Scaling Groups

» Table of contents (CLF-C02) « #

» Disclaimer « #