High availability Flashcards
Types of load balancers
application
network
classic
application load balancer
HTTP and HTTPs traffic
Layer 7
application aware
very intelligent
network load balancer
best suited for balancing TCP where extreme performance is required
layer 4
can handle millions of requests a second w/ ultra low latency
classic load balancer
old school load balancer
can load balance HTTP/HTTPS apps and use layer-7 specific features
can also use strict layer 4 load balancing
Where you want to do just basic round robin
X-Forwarded-For Header
to get the clients actual IPv4 address when it’s been passed through a load balancer
Sticky sessions
allows you to bind a user’s session to specific ec2 instance for duration of the session
Cross zone load balancing
allows load balancer to send load to another AZ
path patterns
allows you to send traffic to a different EC2 instances based on the request URL
Auto scaling components
groups - logical component; webserver group, db group, etc
config templates - instructions on what type ec2 instances to launch
scaling options - specify scaling type
scaling options
maintain current instance levels at all times
scale manually
scale based on schedule
scale based on demand
predictive scaling
Maintain current instance levels at all times
perform periodic health check on running instances.
If unhealthy -> terminate and launch new instance
manual scaling
specify the change in max, min, or desired capacity
scale based on a schedule
scaling actions performed automatically based on date and time
scale based on demand
Lets you define parameters that control the scaling process
using scaling policies
predictive scaling
help you maintain optimal availability and performance
