Read the original article at Autoscaling MySQL on Amazon EC2
Autoscaling your webserver tier is typically straightforward.
Image your apache server with source code or without, then sync
down files from S3 upon spinup. Roll that image into the
autoscale configuration and you’re all set.
With the database tier though, things can be a bit tricky. The typical configuration we see is to have a single master database where your application …