EC2 instance is an amazon virtual machine, there are many EC2 instance types, find below the main ones:

- R: apps that need a lot of RAM -in memory caches
- C: apps that need good CPU – compute / databases
- M: apps that are balanced (think medium) – general / web app
- I: apps that need good local I/O (instance storage) – databases.
- G: apps that need a GPU – video rendering / machine learning.
- T2/T3: burstable instances (up to a capacity)
- T2/T3: unlimited burst

Pricing models:

• On Demand: pay per hour or second with no commitment, it is low cost, flexible and used for short term, dev/testing and you have a predictible price.
• Reserved: you get a significant discount (1y-3y), it is used for apps that have steady state and that require capacity:
  • Convertible reserved instances: long workloads with flexible instances.
  • Scheduled reserved instances, example: every Thu between 3 and 6 pm.
• Spot: you bid whatever price you want for instance, it is used for apps that have flexible start & end times.
• Dedicated instances: no other customers will share your hardware, billing is based on instance.
• Dedicated hosts: you book an entire physical server, for regulatory (no multi-tenant support), great for licensing,

Important: for prod environnement
Termination protection is turned off by default, you must turn it on.

EBS: 5 different types of EBS storage:

• General purpose SSD
• Provisionned iops SSD
• Throughput optimized HDD
• Cold HDD (lowest )
• EBS magnetic

AMI Types (EBS vs instance store):

• For EBS volumes: the root device for an instance launched from the AMI is an EBS volume created from an EBS snapshot.
• For Instance store volumes: the root device for instance launched from the AMI is an instance store volume created from a template stored in S3.
• Instance store volume is an Ephemeral storage: if stopped, you will lose all your data.
• Instance store is physically attached to the machine (EBS is a network drive).
• Instance Store Pros:
  • Better I/O perofrmance
  • Good for buffer / cache / scratch data / temporary content.
• Instance Store Cons:
  • On stop or termination, the instance store is lost.
  • You cant resize the instance store
  • Backups must be operated by the user.
• EBS RAID Options (do it on OS not AWS):
  • RAID0: increase performance (lots of iops), but more risk (if 1 disk fail, data lost).
  • RAID1: increase fault tolerance (mirroring).
  • RAID5 (not recommanded for EBS)
  • RAID6 (not recommanded for EBS)

Elastic Network Interface vs Enhanced Networking vs Elastic Fabric Adapter:

• ENI: elastic network interface, virtual network card
  • For basic networking, create a management network, use a network appliance in your VPC..
  • Low cost
• EN: Enhanced networking: uses single root I/O virtualization, there is 2 types:
  • ENA elastic network adapter: 100Gbps
  • VF virtual function: 10Gbps
• Elastic Fabric Adapter: for machine learning or high performing computing (HPC) or OS bypass.

EBS encryption:

• Data in transit between an instance and an encrypted volume is also encrypted
• Encryption is supported on all Amazon EBS volume types

EFS: Elastic File System

• It grows automatically, great for file server or sharing data between EC2 instances
• You pay for what you use
• EFS support NFSv4 protocol
• You only pay for the storage you use
• Can scale up to the petabytes
• Can support 1000s of concurrent NFS connections
• Data is stored across multiple AZs within a region
• Read After write consistency

Amazon FSx for Windows and for Lustre:

• FSx for windows: built on windows server, use SMB and supports AD users, DFS (Distributed File System).. . Centralized storage for windows, Sharepoint, IIS or other native app for microsoft:
  • Can be accessed from your on-premise infrastructure
  • Can be configured to be MultiAZ (HA)
  • Data is backed up daily to S3
• EFS: is linux only, use it if you need distribution..
• FSx for Lustre: for linux, if you process large data sets, millions of IOPS, machine learning, High Performance Computing (HPC), video processing, electronic design automation, financial modeling.

EC2 Placement Groups:

• Clustered placement group: within a single Availability Zone
  • Pros: Low Network Latency / High network throughput
  • Cons: if the rack fails, all instances fails at the same time.
  • Use case: Big data job that needs to complete fast.
• Spread placement group: individual instances placed in different hardware (rack..), for single instance
  • Pros:
    • Can span across AZs
    • Reduce risk of simultaneous failure
    • EC2 instances are on different physical hardware
  • Cons:
    • Limited to 7 instances per AZ per placement group
  • Use case:
    • App that needs to maximize high availability.
    • Critical apps where each instance must be isolated from failure from each other
  • Partitioned Placement Group: think multiple instances in partition group.
    • Up to 7 partitions per AZ
    • Up to 100s of EC2 instances
    • The instances in a partition do not share racks with the instances in the other partitions.
    • A partition failure can affect many EC2 but won’t affect other partitions.
    • EC2 instances get access to the partition: information as metadata
    • Use case: HDFS, HBase, Cassandra, Kafka

EC2 Hibernate.

• The in-memory (RAM) state preserved.
• The instance boot is much faster (os is not stopped/restarted)
• Under the hood:the RAM state is written to a file in the root EBS volume
• The root EBS volume must be encrypted
• Supported instance families: C, M and R.
• Instance RAM size must be less than 150GB
• Available for OnDemand and Reserved Instances.
• An instance cannot be hibernated more than 60days
• Use cases:
  • long running processing
  • saving the RAM state
  • services that take time to initialize.

EC2 Best practices
Security

• Manage access to AWS resources using IAM roles.
• Implement the least permissive rules for your security group (Firewall).
• Patch, update and secure regularly the operating system and applications on your EC2 instance.

Storage

• Use separate Amazon EBS volumes for the operating system and data.
• Ensure that the data volume persists after instance termination.
• Encrypt EBS volumes and snapshots.

Resource management

• Use instance metadata and custom resource tags to track and identify your AWS resources.
• View your current limits for Amazon EC2 and plan in advance the request of any limit increases.

Backup and recovery

• Backup periodically your EBS volumes using snapshots.
• Create an Amazon Machine Image (AMI) from your instance to save the configuration as a template if needed for future installation.
• Deploy critical components of applications across multiple AZs.
• Monitor and respond to events.
• Test regularly the process of recovering your instances and Amazon EBS volumes if they fail.