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
scaling out vs scaling up
scaling out - use auto scaling groups and add additional EC2 instances
scaling up - increase resources in EC2 instances
Elastic beanstalk
allows you to quickly deploy/manage apps in the cloud
beanstalk handles
- load balancing
- capacity provisioning
- scaling
- app health monitoring
- etc
HA w/ Bastion hosts
w/ NLB
two hosts in separate AZs
Use an NLB w/ health checks to fail over from one host to another
w/ Auto-scaling group
One host in one AZ w/ health checks to fail over from one host to another in a different AZ
Some downtime but cheaper
On-prem AWS services
- Database migration service (DMS)
- Server migration service (SMS)
- AWS application discovery service
- VM import/export
- Download amazon linux 2 as an ISO
DMS - acronym
database migration service
DMS - definition
allows you to move DBs to and from AWS
supports homogenous and heterogeneous migrations
SMS - acronym
SMS - definition
supports incremental replication of on prem servers into AWS
Can be used as a backup or DR tool
AWS application discovery service
gathers info about on-prem data centers
builds a server utilization map and dependency map
helps you plan migration to AWS
VM import/export
migrate existing apps in to EC2
can be used for DR strategy on AWS
can export AWS VMs to on-prem data center
Load balancer IP vs Domain name
load balancers have their own DNS address, you are not given an IP
