Existing paravirtual machine's root will not work with hvm type machine. One thing can do is Use this, the working script is at the bottom of the script. That is used to convert para virtual to hvm. But note this will take extraoridinary downtime. Face it. But it works. Or, Create a new instance and install the softwares from scratch taking the logs, files you need as a backup. And attach the volumes to the new instance. Volumes can be attached without any problem unless they are in the same region. Hope this helps..