Udemy Lecture: Greater loaLB & ASG- Elastic load balancing & Auto scaling groups Flashcards
Scalability means what?
that an application/ system can handle greater loads by adapting
What are the two types of scalability?
-Vertical scalability
-Horizontal scalability (= elasticity)
Scalability is linked but different to high _____________
availability
What does vertical scalability means?
means increasing the size of the instance (ex. Your EC2 instance went from t2.mirco to t2.large)
_____________ is very common for non distributed systems, such databases
Vertical scalability
What does horizontal scalability mean?
increasing the number of instances/ systems for your application
___________ usually goes hand in hand with horizontal scaling
High availability
What does high availability mean?
High availability means running your application / system in at 2 availability zone
What is goal of high availability?
is to survive data center loss (disaster)
What is the difference between scalability, elasticity, and agility?
Scalability- is the ability to accommodate a larger load by making the hardware stronger (scale up) or by adding nodes (scale out)
Elasticity- is once a system is scalable, elasticity means that there will be some “auto-scaling” so that the system can scale based on the load. This is “cloud-friendly”, pay per use, match demand, optimize costs
Agility (not related to scalability- distractor)- new IT resources are only a click away, which means that you reduce the time to make those resources available to your developers from weeks to just minutes
What is a load balancer?
Load balancer are servers thay forward internet traffic to multiple server (EC2 instances) downstream
With a __________ you can load across multiple downstream instances
load balancer
-Spread the load across multiple downstream instances
-Expose a single point of access (DNS) to your application
-Seamlessly handle failure of downstream instances
-Provide SSL termination (HTTPS) for your websites
-High availability across zones
An ____________ is a managed load balancer
ELB (Elastic load balancer)
-AWS guarantees that it will be working
-AWS takes care of upgrades, maintenance, high availability
-AWS provides only a few configuration knobs
What are the 3 different types of load balancer offered by AWS?
-Application load balancer (HTTP/ HTTPS only) - layer 7
-Network load balancer (ultra-high performance, allows for TCP)- layer 4 (lower level)
-Gateway load balancer- layer 3
When you see HTTP/ HTTPS /gRPC protcocols (layer 7) then its ___________
Application load balancer (ALB)
-HTTP routing features
-Static DNS (URL)
When you see TCP/UDP protocols (layer 4) its ____________
network load balancer related (NLB)
-High performance- millions of request per seconds
-Static IP through elastic IP
When you see GENEVE protocol on IP packets (layer 3) then its ____________
related to gateway load balancer (GLB)
-Route traffic to firewalls that you manage on EC2 instances or intrusion detection
What are the different autoscaling group strategies?
- Manual scaling
- Dynamic scaling
- Target tracking scaling
- Scheduled scaling
- Predictive scaling
What is manual scaling
update the size of an ASG manually (change the capacity like from 1 to 2)
What is dynamic scaling?
respond to changing demand
What is target tracking scaling?
Making sure your at your target, ex. “I want the average ASG CPU to stay at around 40%”
What is scheduled scaling?
anticipate scaling based on known usage patterns
What is predictive scaling?
use machines learning to predict future traffic ahead of time & automatically provision the right # of EC2 instances in advance (useful when your load has predictable time-based patterns)
___________ can add or remove instances, but from the same type. They cannot change the EC2 Instances Types on the fly.
Auto Scaling Groups
