EBS Basics

  • EBS volumes are persistent, meaning that they can live beyond the life of the EC2 instance they are attached to.
  • EBS backed volumes are network attached storage, meaning they can be attached/detached to or from various EC2 instances.
  • However, they can only be attached to ONE EC2 instance at a time.
  • EBS volumes have the benefit of being backed up into a snapshot - which can later be restored into a new EBS volume.

EBS Performance:

  • EBS volumes measure input/output operations in IOPS;
    • IOPS are input/output operations per second - how fast data can move in/out of the storage volume.
    • AWS measures IOPS in 256KB chunks (or smaller).
    • Operations that are greater than 256KB are separated into individual 256KB chunks.
      • For example, a 512KB operation would count as 2 IOPS.
  • The type of EBS volume you specify greatly influences the I/O performance (IOPS) your device will receive.
  • It is important as architects to understand if your application requires more (or less) I/O when selecting an EBS volume.
  • Even volumes with "provisioned IOPS" may not produce the performance you expect. If this is the case, an EBS optimized instance type is required, which prioritizes EBS traffic.

Initializing EBS Volumes:

  • New (only New) EBS volumes no longer need to be "pre-warmed".
  • New (only New) volumes will receive their maximum performance at the moment they are created.
  • Volumes created from an EBS snapshot must be initialized.

  • Initializing occurs the first time a storage block on the volume is read - and the performance impact can be impacted by up to 50%.

  • You can avoid this impact in production environments by manually reading all the blocks.

EBS Volumes:

General Purpose SSD:

  • Use for dev/test environments and smaller DB instances.
  • Performance of 3 IOPS/GiB of storage size (burstable with baseline performance).
  • Volume size of 1GiB to 16TiB.
  • Considerations when using T2 instances with SSD root volumes (bustable vs. baseline performance).

Provisioned IOPS SSD:

  • Used for mission critical applications that require sustained IOPS performance.
  • Large database workloads.
  • Volume size of 4GiB to 16TiB.
  • Performs at provisioned level and can provision up to 20,000 IOPS per volume.

Magnetic:

  • Low storage cost.
  • Used for workloads where performance is not important or data is infrequently accessed.
  • Volume size of Min 1GiB Max 1TiB.

EC2 Instance Store Volume:

  • Instance store volumes are virtual devices whose underlying hardware is physically attached to the host computer that is running the instance.
  • Instance store volumes are considered ephemeral data, meaning the data on the volumes only exists for the duration of the life of the instance.
  • Once the instance is "stopped" or "shutdown", the data is erased.
  • The instance can be rooted and still maintain its ephemeral data.

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