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EBS.md

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EBS

  • General:
    • When you create an EBS volume in an Availability Zone, it is automatically replicated within that zone to prevent data loss due to failure of any single hardware component. Thus, a volume can't "survive" an Availability Zone general failure (data is only replicated within one AZ).
    • An EBS volume is off-instance storage that can persist independently from the life of an instance.
    • An EBS volume can only be attached to one EC2 instance at a time in the same AZ.
    • EBS volumes support live configuration changes while in production which means that you can modify the volume type, volume size, and IOPS capacity without service interruptions.
    • By default, EBS volumes (both EBS and instance-store) that are created and attached to an instance at launch are deleted when that instance is terminated. This can be changed by setting the DeleteOnTermination flag to false.
  • Types:
    • General Purpose SSD (gp2): Max 10,000 IOPS. Good balance between performance and cost.
    • Provisioned IOPS SSD (io1): Max 32,000 IOPS. Best performance, most expensive.
    • Throughput Optimized HDD (st1): Max 500 IOPS. Low cost, fastest HDD available.
    • Cold HDD (sc1): Max 250 IOPS: Lowest cost, slowest disk.
    • 50:1 is the maximum ratio of provisioned IOPS to requested volume size in Gibibyte (GiB).
    • The maximum size for a EBS volume is 16TiB.
  • Snapshots:
    • Snapshots are incremental (the first one may take a while).
    • Snapshots can be done with the volume in use (and you can keep using it while the snapshot is in progress).
    • Snapshots can be scheduled with Amazon Data Lifecycle Manager (Amazon DLM).
    • Snapshots of encrypted volumes are automatically encrypted.
    • Volumes that are created from encrypted snapshots are automatically encrypted.
    • When you copy an unencrypted snapshot that you own, you can encrypt it during the copy process.
    • When you copy an encrypted snapshot that you own, you can reencrypt it with a different key during the copy process.
    • You can create a copy of a volume on a different AZ by making a snapshot and restore it to the new volume.
  • Encryption:
    • The following data can be encrypted:
      • Data at rest inside the volume
      • All data moving between the volume and the instance
      • All snapshots created from the volume
      • All volumes created from those snapshots
    • You can use your own-keys or Amazon-managed keys to encrypt EBS volumes with KMS.