Using instance volume as root space instead of EBS volume

Hi There

Only the following instance types support an instance store volume as the root device: C3, D2, G2, I2, M3, and R3.

You can choose between AMIs backed by Amazon EC2 instance store and AMIs backed by Amazon EBS. We recommend that you use AMIs backed by Amazon EBS, because they launch faster and use persistent storage.

See https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/RootDeviceStorage.html