Oracle 5.0 Reference Manual page 1352

Most types of scale-out topology that you would use with your own hardware can be used and applied
within the EC2 environment. However, use the limitations and advice already given to ensure that any
potential failures do not lose you any data. Also, because the relative power of each EC2 instance is so
low, be prepared to alter your application to use sharding and add further EC2 instances to improve the
performance of your application.
For example, take the typical scale-out environment shown following, where a single master replicates
to one or more slaves (three in this example), with a web server running on each replication slave.
You can reproduce this structure completely within the EC2 environment, using an EC2 instance for the
master, and one instance for each of the web and MySQL slave servers.
Note
Within the EC2 environment, internal (private) IP addresses used by the EC2
instances are constant. Always use these internal addresses and names
when communicating between instances. Only use public IP addresses when
communicating with the outside world - for example, when publicizing your
application.
To ensure reliability of your database, add at least one replication slave dedicated to providing an
active backup and storage to the Amazon S3 facility. You can see an example of this in the following
topology.
Deploying a MySQL Database Using EC2
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