Cloud elasticity is the ability to increase or decrease resource capacity as demand changes. On AWS, on-demand scaling reduces the need to purchase infrastructure for uncertain future capacity. section 17.0
Elasticity applies to both growth and reduction: an application can scale from one EC2 instance to thousands, expand storage from gigabytes to petabytes, and remove unused capacity when demand falls. section 17.0
AWS implements elastic compute capacity with:
- Auto Scaling groups, which manage a fleet of similar EC2 instances. section 17.0
- Scaling policies, which adapt the fleet size to the system's current load. section 17.0
A web shop's changing traffic
A web shop may need more instances during the day, on weekdays, or before Christmas, then remove capacity at night, on weekends, or after seasonal demand declines. section 17.0
Use the traffic-pattern figure to compare recurring demand with the capacity changes elasticity enables. section 17.0
