DEV Community

Cover image for All you need to know about EC2 instance

Posted on

All you need to know about EC2 instance

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

Alt Text

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

  • 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.


  • 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.

Top comments (0)