title: Amazon EC2 - Swap root instance store device with EBS device
body: <p>I have an EC2 instance with "instance store" device as a root device.
  Now, I would like to attach an EBS volume to that same instance,
  only that I want <b>it to be</b> the root device.
  Is that possible?
  What happens to the instance store device in such case?</p>
  
  <p>Thanks in advance</p>