5. EC2 Flashcards
List the EC2 Instance Launch Types.
- On-Demand
- Reserved (reserved, convertible reserved)
- Spot Instances
- Dedicated Instances
- Dedicated Hosts
new: - Savings Plans
- Capacity Reservations
What are On-Demand instances?
- Best for short-term and uninterrupted workloads
- Highest cost launch type
What are Reserved instances?
- 1 or 3 years only
- recommended for steady-state usage applications with long workloads (think database)
- you reserve specific instance attributes (instance type, region, tenancy, OS)
- best for steady state applications (databases)
What are Convertible Reserved instances?
- 1 or 3 years only
- recommended for long workloads
- can change the EC2 instance type
- best for long workloads with flexible instances
What are Spot instances?
- best for workloads that are resilient to failure (batch jobs, data analysis, image processing, etc)
- not great for critical jobs or databases
- CHEAP
- can lose instances (less reliable)
What are Dedicated instances?
- instances run on hardware that’s dedicated to you
- may share hardware with other instances in same account
- no control over instance placement (can move hardware after Stop/Start)
- no instance placement control
What are Dedicated Hosts?
- book an entire physical server
- control instance placement
- most expensive option
- useful for software with complicated licensing models and/or companies with strong regulatory or compliance needs
What is EBS?
Elastic Block Storage
- a network drive you can attach to your instances while they run, allowing your instances to persist data
- Can be attached to only one instance at a time
- Are locked at the Availability Zone (AZ) level
- To migrate an EBS volume across AZ: Take a snapshot and restore the snapshot to another AZ
- Root EFS volumes of instances get terminated by default if the EC2 instance gets terminated (you can disable that)
What is EFS?
Elastic File Storage
- Mounting 100s of instances across AZ
- EFS share website files (WordPress)
- Only for linux instances (NOT Windows)
- EFS has a higher price point than EBS
- Highly available, scalable, expensive (3x gp2), pay per use
What is an EC2 Instance Store?
- Physical disk attached to the physical server where your EC2 is
- Very high IOPS (because physical)
- Block storage (just like EBS)
- Cannot be increased in size
- Risk of data loss if hardware fails
What is EC2 User Data?
EC2 User Data is used to automate boot tasks such as:
- installing updates
- installing software
- downloading common files from the internet
The EC2 User Data Script runs with the root user
- script only runs once at instance first start
What is an AMI?
Amazon Machine Image
- image used to create instances
- AWS comes with base images (Ubuntu, Windows, etc)
- images can be customized at runtime using EC2 User Data
- AMIs are built for a specific AWS region
What is an ENI?
Elastic Network Interface
- logical component in a VPC that represents a virtual network card
- bound to a specific AZ
- you can create ENI independently and attach them on the fly (move them)
Security groups contain what kind of rules?
Security groups only contain ALLOW rules
If your application throws a timeout error, what is the issue?
Security Group Issue
