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Unlike EBS volumes, instance store volumes are ephemeral. This means that when the instances they're attached to are shut down, their data is permanently lost. So, why would you want to keep your data on an instance store volume more than on EBS?

 Instance store volumes are SSDs that are physically attached to the server hosting your instance and are connected via a fast NVMe (Non‐Volatile Memory Express) interface.

 The use of instance store volumes is included in the price of the instance itself.

 Instance store volumes work especially well for deployment models where instances are launched to fill short‐term roles (as part of autoscaling groups, for instance), import data from external sources, and are, effectively, disposable.

Whether one or more instance store volumes are available for your instance will depend on the instance type you choose. This is an important consideration to take into account when planning your deployment.

Even with all the benefits of EBS and instance storage, it's worth noting that there will be cases where you're much better off keeping large data sets outside of EC2 altogether. For many use cases, Amazon's S3 service can be a dramatically less expensive way to store files or even databases that are nevertheless instantly available for compute operations.

You'll learn more about this in Chapter 3, “AWS Storage.”

The bottom line is that EBS volumes are likely to be the right choice for instances whose data needs to persist beyond a reboot and for working with custom or off‐the‐shelf AMIs. Instance store volumes are, where available, useful for operations requiring low‐latency access to large amounts of data that needn't survive a system failure or reboot. And non‐EC2 storage can work well when you don't need fantastic read/write speeds, but you wish to enjoy the flexibility and cost savings of S3.