Elastic Load Balancing & Auto Scaling Flashcards
Scalability
Linked to high availability.
Ability to accommodate larger loads by making hardware stronger (scale-up) or add nodes (scale out)
Vertical scalability
increasing the SIZE of the instances
Horizontal scalability
increasing the # of instances
scale-up
increasing instance type (ex: m4.large to a m4.xlarge)
scale-down
decreasing instance type (ex: m4.xlarge to a m4.large)
High Availability
Horizontal scalability.
Running app in at least 2 A.Z.
Elasticity
Cloud native auto-scaling system can scale based on load.
can instantly grow ( to maintain performance) or shrink ( to reduce costs).
to scale resources out or in (up or down) based on changes in demand.
Elasticity vs Scalability
Elasticity = AUTO scaling up/down.
Scalability = ability to increase workload size STATICALLY
Load Balancing
Servers forward intent traffic to multiple EC2 instances
AWS ELB
Elastic Load Balancer
regularly perform health checks and distribute traffic only to healthy instances (Balance load across multiple EC2 instances.)
3 Types of ELB
Application, Network, Classic
Service that lets us be elastic on AWS?
Load Balancing (ELB)
Auto Scaling Group
contains a collection of EC2 instances for auto scaling.
ex: can handle changing load on your app by adding/removing computing resources
Types of Auto Scaling
manual scaling
dynamic scaling
predictive scaling
scale out
add more EC2 instances to your Auto Scaling Group, to match increased load
