EBS (Elastic Block Store)

EBS

A scalable block storage service provided by AWS for EC2 instances

• Allows to attach virtual hard drives to EC2 instances
• Focuses on EC2 instances only and you can’t use with other services
  • Block storage
• It is a regional service, so the region you select (on top right) matters
  • Volumes are created in specific regions, and can be attached to EC2 instances of the same regions
• EBS volumes are part of free tier, but it is limited
• AWS automatically creates an EBS volume (let’s say 30GB).
• Whilst the root volume typically is deleted together with the instance, other volumes survive instance termination unless configured otherwise
• Resources
  • EBS vs EFS
  • EBS vs EFS vs S3

With EC2 instances

• diagram
• When you launch an EC2 instance, you can automatically add EBS volumes to that instance
  • you can add multiple volumes, give those a name, and choose the kind, size, etc
  • Once the instance starts, you have to structure each volume manually
    • New volumes are raw storage → They don’t have a file system yet.
    • You must format them → Just like adding a new hard drive to a computer.
    • You must mount them → So the OS can recognize and use the storage.
• Can be formatted and structured as needed
  • with AWS CLI from in the instance
  • so you can connect to your instance with SSH → mount & format your hard drive

EBS Core Features

• diagram
• Different types of hard drives you can choose
  • You can find a perfect hard drive for your specific workload
• Elastic volumes
  • you can scale the volumes as needed, instead of adding an extra volume!
  • you can scale dynamically (automatically)
  • extra feature that should be managed
• Snapshots
  • You can save a snapshot of a EC2 instance and save that snapshot on an EBS volume, then restore that instance/data for a future instance you’re launching
  • useful to make sure you’re not losing your data as you terminate your EC2 instance
  • reminds me of creating snapshots for linux
• Multi-Attach
  • By default when you create an EBS volume, you attach to a single EC2 instance
  • Multiple instances might be working on the same kind of task, and might need to access the same files
  • Only supported by some instance types
  • tricky to set up → resolve file conflicts

EC2 Instance storage

A special term separate from EBS

• diagram
• All EC2 instances have base storage
  • base storage is where the OS and the base software (by the AMI) is installed on
  • There are two types of storage you can use for this: EC2 Instance Store vs. EBS
    • when you pick an AMI, you also pick the type of storage (root device type)
    • Most AMIs have EBS-backed
• EC2 Instance Store
  • non-EBS backed storage
  • hard drive, part of the machine/rack in the data center
  • data is lost if the instance stops or is terminated
  • less common
• EBS-backed
  • AWS automatically creates an EBS volume (let’s say 30GB) when you launch an EC2 instance
  • data persists even if the instance stops
  • most common, the default option