I have been unsuccessful in reading the ephemeral block device mapping back (in either describe_images, describe_instances calls or in aws console - they all seem to be completely ignoring the ephemeral mapping) but when I launched the image I did get a /dev/sdb in it.
Edit: changed sdc to sdb in the documentation as that's what you get by default with instance storage.
Based on http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/index.html?Using_AddingDefaultLocalInstanceStorageToAMI.html.
I have been unsuccessful in reading the ephemeral block device mapping back (in either describe_images, describe_instances calls or in aws console - they all seem to be completely ignoring the ephemeral mapping) but when I launched the image I did get a /dev/sdb in it.
Edit: changed sdc to sdb in the documentation as that's what you get by default with instance storage.