Engine Yard does not recommend using the provided AWS/S3 account for Asset Storage, because Engine Yard Cloud relies on specific and important resources in this AWS account. Accidental alteration of these resources can result in an unstable environment and even data loss.
If you close your Engine Yard account, all your stored assets are deleted when the account is closed.
Engine Yard does recommend that you set up a separate S3 account to store your assets. That way, you are in full control of your assets. For information about how to serve assets from an S3 account using fog and CarrierWave, see Use CarrierWave (and optionally fog) to upload and store files.