There are two different ways of setting up a redundant MySQL database on Amazon EC2.  In both cases, there will be a Master-DB and Slave-DB with replication for failover and recovery.  The core difference between each setup is how the backups are saved.  See Overview of MySQL-EBS Setups for more details about the various types of MySQL database setups.

WARNING!  Before you set up your Master/Slave databases, you should complete each step of the Deployment Setup.  Each database tutorial assumes that you have already setup your SSH keys, security groups, etc.

Below are the three main types of MySQL database setups:

• MySQL-S3 - Backups of the database are saved directly to S3 as *.tar files.  ("MySQL Bootstrap" and "MySQL Additional" ServerTemplates)
• MySQL-EBS (no Striping) - Backups of the database are saved as EBS snapshots to S3. 
• MySQL-EBS (w/ Striping) - Backups of the database are saved as a set of EBS snapshots to S3.