Elastic Block Storage

  • An Amazon EBS volume is a durable, block-level storage device that you can attach to a single EC2 instance. ​
  • An EBS (Elastic Block Store) Volume is a network drive you can attach to your instances while they run​
  • An EC2 machine loses its root volume (main drive) when it is manually terminated.​

It is a network drive (i.e. not a physical drive)​

  • It can be detached from an EC2 instance and attached to another one quickly​

It is locked to an Availability Zone (AZ)​

  • An EBS Volume used in one AZ cannot be used in another AZ of the same region.
    e.g: If the EBS is attached in us-east-1a cannot be attached to us-east-1b​​
  • In order to move the EBS to another region you need to take snapshot, transfer the snapshot to another region and the reattach it to the transfered region

Types of EBS volumes

  1. GP2 (SSD):
    General purpose SSD volume that balances price and performance for a wide variety of workloads​.
  2. IO1 (SSD):
    Highest-performance SSD volume for mission-critical low-latency or high throughput workloads​.
  3. ST1 (HDD): Low cost HDD volume designed for frequently accessed, throughput intensive workloads​
  4. SC1 (HDD): Lowest cost HDD volume designed for less frequently accessed workloads​.

EBS Snapshots

  • You can take backup of EBS volume with the help of snapshot feature available in AWS.
  • These snapshots are incremental and the backup only the changed data in incremental way of backups.
  • These snapshots uses storage to store and are stored in S3.
  • You can take up to 10,000 snapshots.
  • Charges of the snapshots are based on the amount of
    data stored.
  • If the EBS volume is encrypted the snapshot also gets encrypted automatically and vice-versa.
  • Snapshots can be copied to another regions and Availability zones.
  • You can schedule the snapshot to be taken automatically using ‘Amazon Data Lifecycle Manager’.

Instance Store or Ephemeral Storage

  • Some instance do not come with root EBS volumes instead they come with Instance Store (also called as ‘ephemeral storages’)​.
  • Ephemeral means temporary, i.e. data stored last for a very short time​.
  • It provides temporary block-level storage for your instance.​
  • This storage is located on disks that are physically attached to the host computer.​
  • On rebooting the instances the data survives but if the instance is stopped or terminated the instance store data is lost.​
  • The instance store volumes cannot be resized like EBS.​