MySQL Database-as-a-Service on Amazon Web Services
ClouSE is the Cloud Storage Engine for MySQL that can utilize cloud storage such as Amazon S3 to store relational and blob (a.k.a. structured and non-structured) data. ClouSE provides fully functional, transactional and ACID-compliant relational data management on top of cloud storage.
On the other hand, Xeround (pronounced zeh-round) is a service that replaces your existing MySQL database and provides seamless MySQL scalability and high availability. Xeround runs in the cloud, allowing you to scale your database up or out automatically, and maintain availability even in the event of failure. Currently, you can run your database on Amazon Web Services and on Rackspace, as well as via the Heroku platform, with additional cloud service providers being added.