I would like to have a highly-available MySQL system, with automatic failover, running on Amazon EC2 instances.
The standard approach to solving this is problem Heartbeat + DRBD, but I've found a lot of posts suggesting DRBD doesn't work on EC2, though none saying exactly why. Obviously, a serial heartbeat or distinct network is out of the question in the virtualised environment. It would also be good to have the different servers be in different availability zones, but we're getting into a much harder problem there.
What are peoples' opinion on having a high uptime solution in "the cloud"?
Note: This question was asked before RDS with multi-AZ was announced, which is the nice automatic answer for today's modern IT professional. :)