Created : March 26, 2020

This note was taken while learning AWS on Udemy.

EC2 = Elastic Compute Cloud

  • virtual servers in the cloud
  • a web service

    • provide resizable compute capacity in the cloud
    • reduce time required to obtain/boot new server instances to mins
    • allow you to quickly scale capacity as your computing requirements change
  • S3 = storage in the cloud / EC2 = compute in the cloud

Pricing models


  • pay a fixed rate by hour(or second)
  • no commitment, no upfront payment


  • provide capacity reservation
  • with steady state/predictable usage
  • offer significant discount on hourly charge
  • 1yr or 3yr contract terms
  • Standard : the more pay upfront, the longer the contract, the greater the discount.
  • Convertible : allow you to change between different instance types
  • Scheduled : available to launch within the time windows you reserve


  • bid whatever price for Amazon's excess capacity
  • depend on Amazon's supply&demand (like stock market)
  • set the price you want to bid

    • if it hits that price - have your instance
    • if it goes above price - lose your instance
  • for applications that have flexible start/end times
  • if terminated by EC2, no charged for a partial hour of usage
  • but if you terminate by yourself, you will be charged for partial.

Dedicated Hosts

  • physical EC2 server dedicated for your use
  • for regulatory requirements
  • great for licensing
  • can be purchased on-demand/reservation

Instance Types

ec2 1

  • Associate 시험에선 그닥 중요X (Professional 시험에서 중요함)
  • 알파벳뒤의 숫자들은 계속 바뀌기 때문에 신경쓰지말것


  • F : for FPGA
  • I : for IOPS
  • G : Graphics
  • H : High Disk Throughput
  • T : Cheap general purpose (think T2 Micro)
  • D : for Density
  • R : for RAM
  • M : Main choice for general purpose apps
  • C : for Compute
  • P : Graphics (think Pics)
  • X : Extreme memory
  • Z : Extreme memory AND CPU
  • A : Arm-based workloads
  • U : Bare Metal

Launch EC2

  • termination protection is turned off by default. Must turn it ON.
  • on an EBS-backed instance,

    • default action is for root EBS volume to be deleted when the instance is terminated.
  • EBS Root Volumes of default AMI's can be encrypted.

Security Groups

  • all inbound traffic is blocked by default.

    • if you allow traffic in, that traffic is automatically allowed back out again.
  • all outbound traffic is allowed.
  • change to security groups : take effect immediately.
  • can have any number of EC2 instances within a security group.
  • can have multiple security groups attached to EC2 instances.
  • stateful : no need to change inbound/outbound ports (enabled automatically)
  • cannot block specific IP address using security groups

    • use Network ACL(Access Control Lists) instead
  • can specify allow rules, not deny rules

EBS (Elastic Block Store)

  • virtual hard disk in the cloud
  • provide persistent block storage volumes with EC2
  • each EBS volume is automatically replicated within AZ to protect you from component failure
  • EBS always in the same AZ with EC2

5 types of EBS storage

ec2 2

  • API name 외우기


  • a durable, block-level storage device
  • use EBS volumes as primary storage for data that requires frequent updates
  • always be in same AZ as EC2 instance
  • To move EC2 volume from one AZ to another

    • take a snapshot of it,
    • create an AMI from snapshot,
    • use AMI to launch EC2 instance in new AZ.
  • To move EC2 volume from one region to another

    • take a snapshot of it,
    • create an AMI from snapshot,
    • copy AMI from one region to the other,
    • use copied AMI to launch new EC2 instance in new region.


  • point-in-time copy of EBS volume, save to S3

    • when you take snapshot, that's how volume existed at that particular point in time.
    • = a photograph of disk
  • incremental(증분식) copies of data

    • only unique blocks that have changed since last snapshot are moved to S3.
    • 마지막 스냅샷 이후 변경된 블록만이 저장됨
  • first snapshot - take some time to create
  • each snapshot contains all of the information that is needed to restore your data (from the moment when the snapshot was taken) to a new EBS volume.
  • To create a snapshot for EBS volumes that serve as root devices, you should stop instance before taking snapshot.

    • can take a snapshot while instance is running as well.
  • can create AMI(Amazon Machine Image)'s from snapshots
  • can change EBS volume sizes on the fly, including changing size&storage type.

EBS vs Instance Store

  • Root device type

    • EBS
    • Instance store
  • select AMI based on

    • Region
    • OS (Operating System)
    • Architecture (32bit or 64bit)
    • Launch Permissions
    • Storage for the Root Device/Root Device Volume : Instance Store / EBS Backed Volumes
  • All AMIs are categorized as

    • backed by Amazon EBS
    • or backed by instance store

EBS Volumes

  • root device for an instance launched from AMI
  • created from EBS snapshot
  • can be stopped

    • you'll not lose data even if it's stopped
  • ROOT volumes will be deleted on termination

    • can tell AWS to keep root device volume

Instance Store Volumes

  • created from a template stored in S3
  • cannot be stopped

    • ephemeral storage
    • if underlying host fails and it's stopped, you'll lose all data
  • ROOT volumes will be deleted on termination

Both can be rebooted - will not lose data

ENI vs EN vs EFA

ENI (Elastic Network Interface)

  • virtual network card
  • for basic networking
  • for when you need

    • separate management network to production network
    • separate logging network
    • at low cost
    • → use multiple ENIs for each network

EN (Enhanced Networking)

  • use single root I/O virtualization (SR-IOV)
  • to provide high-performance networking capabilities on supported instance types
  • can be enabled using

    • ENA (Elastic Network Adapter) : support network speeds up to 100 Gbps
    • Intel 82599 VF (Virtual Function) interface : up to 10 Gbps (used on older instances)
    • 시험에서 ENA, VF가 주어지면 주로 ENA를 선택하는 문제
  • for when you need

    • speed between 10Gbps ~ 100Gbps
    • reliable, high throughput

EFA (Elastic Fabric Adapter)

  • a network device
  • can attach to EC2 instance
  • for when you need

    • to accelerate HPC(High Performance Computing) & machine learning applications
    • to do an OS by-pass

Encrypted Volumes & Snapshots

  • snapshots of encrypted volumes : encrypted automatically
  • volumes restored from encrypted snapshots : encrypted automatically
  • can share snapshots, only when they're unencrypted.

    • shared with other AWS accounts or made public
  • can encrypt root device volumes when you create EC2 instance.
  • but, if you didn't encrypt that time, (when you had unencrypted volumes)
  • how to make it encrypted?

    • 1.create a snapshot of unencrypted root device volume
    • 2.create a copy of snapshot, and select encrypt option
    • 3.create an AMI from encrypted snapshot
    • 4.use that AMI to launch new encrypted instances


  • a monitoring service to monitor performance. (like trainer in gym)
  • can monitor applications that run on AWS.
  • Standard monitoring = 5 minutes (by default)
  • Detailed monitoring = 1 minutes
  • can create CloudWatch alarms which trigger notifications.


  • monitors API calls in AWS platform. (all about auditing. like CCTV camera)
  • increase visibility into your user,resource activity
  • by recording AWS management console actions & API calls.
  • you can identify which users & accounts called AWS, the source IP address from which calls were made, and when calls occurred.

AWS Command Line

  • can interact with AWS from anywhere in the world just by using CLI(Command Line).
  • you will need to set up access in IAM.

IAM Roles with EC2

  • roles are more secure than storing access key/secret access key on individual EC2 instances.
  • easier to manage.
  • can be assigned to EC2 instance after it's created using console & command line.
  • universal - use them in any region.

EFS (Elastic File System)

  • a file storage service for EC2 instances.
  • EBS vs EFS

    • EBS : can mount virtual disk to only one EC2 instance. (no more than 1)
    • EFS : can share among EC2 instance
  • provide simple interface - can create, configure file systems quickly & easily.
  • storage capacity is elastic - growing & shrinking automatically as you add and remove files
  • great way to share files between different EC2 instances
  • when you need - distributed, highly resilient storage for Linux instances & Linux-based applications

< Exam tips >

  • support NFSv4 (Network File System version 4) protocol
  • only pay for the storage you use

    • no pre-provisioning required
  • can scale up to petabytes
  • can support thousands of concurrent NFS connections
  • data is stored across multiple AZ's within a region
  • read after write consistency


  • FSx for Windows

    • a managed Windows Server
    • runs SMB-based (Windows Server Message Block) file services
    • designed for Windows & Windows applications
    • when you need - centralised storage for Windows-based applications
  • FSx for Lustre

    • designed specifically for fast processing of workloads
    • for machine learning, HPC(High Performance Computing), video processing, EDA(Electronic Design Automation)
    • can store data directly on S3
    • when you need - high-speed, high-capacity distributed storage

EC2 Placement Groups

  • only certain types of instances can be launched in a placement group.

    • Compute / Memory / Storage Optimized, GPU
  • can't merge placement groups
  • can move an existing instance into a placement group

    • before move instance, instance must be in the stopped state
    • can move/remove instance using CLI or SDK (console X)


  • a group of instances within a same, single AZ

    • can't span multiple AZ
  • for low network latency, high network throughput
  • only certain instances allowed
  • recommended homogenous instances within clustered placement groups.


  • a group of instances that are each placed on distinct underlying hardware
  • protect from hardware failure
  • for applications that have a small number of critical EC2 instances that should be kept separate from each other.


  • EC2 divide each group into logical segments called partitions.
  • each partition within a placement group has its own set of racks
  • each rack has its own network & power source
  • no two partitions share same racks

    • allow you to isolate impact of hardware failure within your application

< Spread vs Partitioned >

  • both : can span multiple AZ, but should be in same region
  • the number of EC2 instance

    • Spread : for single instance partition.
    • Partitioned : for multiple EC2 instances within a partition.

WAF (Web Application Firewall)

  • let you monitor HTTP/HTTPS requests that are forwarded to CloudFront, Application Load Balancer or API Gateway.
  • let you control access to your content.
  • can configure conditions
  • how to block malicious IP addresses

    • use WAF
    • use Network ACLs