Is it just me that thinks it a bit wrong that they don't know/care how many db servers they run? If I was running something like that I'd want to know that number.
at their level, it's like you worrying how many meg your apache server is taking. I understood in the post that they have an auto-scaling tool that starts, mounts and ends (when appropriate) databases servers
I've worked in some environments with pretty massive databases... Every one has known how many servers they have (and the overall capacity). Most have some pretty serious capacity measurement, monitoring and planning methods.
So yeah, I still find it a bit odd. Each to their own I guess.
Sure, I guess if money isn't an issue and you just want the job done, that's what you do to scale.
As long as the fully optimized to start with, and continually monitor that...
I think that you definitely want an architecture that can handle random failures of database servers. Thus you never know exactly how many you have at a specific time. That's the whole point.
I can understand that with a bank of hot spares or use of a service like EC2 or wild traffic swings, the exact number at any one moment becomes less relevant. But it would be nice for them to have given a historical average (and even, typical variance), based on their logs of actual machines dynamically brought into or out of service.
