AWS EC2: AMI vs instance type EBS selection-CodePudding

While creating EC2 instance on AWS, I see following AMI options:

Amazon Linux 2 AMI (HVM) - Kernel 5.10, SSD Volume Type

macOS Monterey 12.2.1 - ami-00aa9c0d2393d0139 The macOS Monterey AMI is an EBS-backed, AWS-supported image

First option tells that disk storage is SSD volume type which I assume means that storage used is instance's local storage. Second option tells that storage is elastic block storage. I opt for first one.

Then on next step for instance type:

Why does it displays 'EBS only' for 'Instance Storage(GB)' column as in previous step I opted for non-EBS type? Are those unrelated?

CodePudding user response：

An AMI will always restore to an EBS volume (or multiple EBS volumes). An AMI is really just a snapshot of one or more EBS volumes, plus some metadata. EBS volumes can be SSD or Magnetic. Your assumption that "SSD Volume Type" indicated local instance storage is incorrect.

Instance storage is ephemeral. An EC2 server never boots from an instance storage volume. Certain instance types come with instance storage that are good for things like fast temp folders, caches, etc. But instance storage volumes can't be saved to snapshots or AMIs, can't be persisted across stops/start cycles, and can't be moved between EC2 instances.