[mrkurt]

They actually said 4. Two shards with slaves for redundancy. It was apparently working fine until they lost track of what was going on. :)

[marclove]

Yea but like you said, since half of them are just for redundancy, they were in effect only running 2 database servers. I must say I find it stunning that a service with that much traffic, especially one with an infrastructure that requires the entire database to be in-memory, would be operating with just 2 database servers running on EC2.

I know hindsight is 20/20, but I can't imagine the foresight was any worse than 20/30.