All our persistent storage is on "ephemeral" drives. If we lose the instance, we lose the data, so we have a lot of redundant slaves and backups (see my other comment).
PS great article
Except for t1 and m3, which have zero ephemeral storage.
Just a tongue-in-cheek comment: Those instances also cost over $2000 USD per month. For the same money you could buy a new Dell Server with 2-4 SSDs, every month. ;)
In this case, I had about 8 million output files from a Hadoop job that I needed to process with MySQL- it was perfect!
http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/In...
However, what do you do if there's a massive outage that affects most or all of your instances simultaneously? Diversification that fails when you need it the most isn't very helpful.
Of course, east-1 has fallen off the map entirely on at least one occasion -- for that reason we keep a "seed" set of warm databases in us-west; if east-1 were to have an extended outage we have a disaster recovery plan that involves transferring DNS to IPs in west and spinning up new app instances there.