Looking for suggestions to Migrate Amazon RDS Large Instance to non-amazon host - Live We have an Amazon RDS Large instance with a database of about 20GB that needs to be migrated without having to take our website down or minimize downtime to less than a couple of hours. 

And I am looking for strategies in which this could work effectively? Our RDS has both innodb and myisam tables.  How possible is this to do while live without corrupting data and what kind of time do you think it would take to migrate a 21 Gb db? Would it be wise to migrate first to a ec2 server so we would have more capabilities? Can you create a read-only replication of the main RDS and clone that to the EC2 for more protection?
Thoughts?
Dump RDS and import it into mysql that holds all data in RAM disk:


Buy strongest possible EC2 instance that might hold your database in memory twice (you might prepare everything on a small instance and then ramp it up)
Create RAM disk, install and configure mysql 5.6 to hold both data and redolog on the RAM disk
Stop your db-using services, dump the RDS directly into the RAM-backed mysql
stop mysql, rsync the DB to a final place, kill the machine


You should do a dry run to estimate expected downtime.