Elastic Load Balancing (ELB) & Auto Scaling Groups (ASG) Flashcards
1
Q
What is Scalability?
A
- Scalability: application / system can handle greater loads by adapting
- Vertical and Horizontal
2
Q
What is Vertical Scalability?
A
- increasing the size of the instance
- zb. von t2.micro auf t2.large upgraden
- für non-distributed systems (database)
3
Q
What is Horizontal Scalability?
A
- increasing the number of instances for your application (easier in AWS)
- for distributed systems (web apps)
4
Q
What is High Availability?
A
- running your application in at least 2 Availability Zones (AZ)
- goes hand in hand with horizontal scaling
- goal = survive data center loss (disaster)
5
Q
High Availability & Scalability For EC2
A
- Vertical Scaling: Increase instance size
- Horizontal Scaling: Increase number of instances (ASG and ALB)
- High Availability: instances for same app across multi AZ (ASG and ALB multi AZ)
6
Q
What is Elasticity?
A
- Auto-scaling based on load to optimize costs
7
Q
What is Agility?
A
Rapid provisioning of IT resources in minutes instead of weeks
8
Q
What is load balancing?
A
- forwards internet traffic to multiple servers (EC2 Instances) downstream
9
Q
Elastic Load Balancer (ELB)
A
- a managed load balancer
- 3 kinds of load balancers (ALB, NLB, GWLB)
10
Q
Application Load Balancer (ALB)
A
- for Layer 7
- HTTP(S), gRPC, Static DNS (URL)
11
Q
Network Load Balancer (NLB)
A
- for Layer 4
- TCP/UDP, high performance, static IP
12
Q
Gateway Load Balancer (GWLB)
A
- for Layer 3
- GENEVE, Route Traffic to Firewalls, Intrusion detection
13
Q
What’s an Auto Scaling Group (ASG)?
A
- scale out/in to match in/decreased load
- ensures min and max number of machines running
- Automatically register new instances to a load balancer
- Replace unhealthy instances
14
Q
Auto Scaling Groups – Scaling Strategies
A
- Manual Scaling
- Dynamic Scaling (Simple/Step, Target Tracking, Scheduled and Predictive Scaling)
