Confusing instance storage details for AWS instance types

[lobanov]

Description

The page listing different instance types available on AWS shows ephemeral-storage resource, and, as far as I can see, for every instance type the page says ephemeral-storage: 17Gi.

I was under impression that it is directly attached instance storage, which is not available on every instance type. For example, i4i.16xlarge should have 15 GB, but c7i-flex.8xlarge should not have any.

I can also see the label karpenter.k8s.aws/instance-local-nvme which seems to have a correct value, but it's name is confusing, because not every instance with instance storage has NVMe onboard, it could be just SSD.

Would be good to know what is the correct way to request a node with directly attached SSD storage through Karpenter, and if ephemeral-storage is the right resource to use for that?