It's much easier to have a higher ratio when the absolute numbers are higher. Fewer than 2 admins means no vacations, and a team of 3 is often more comfortable.
I agree with rarrrrrr, having been the only admin or in a team of two, vacations can be tough. I would gladly work in a team of three if I had the choice.
I haven't watched the talk yet, but it's quite possible that having more sysadmins is what allows them to use 40 servers. One guy might have needed 80 servers to accomplish the same work because he's too busy to optimize anything. :)
They must be lumping internal IT tasks in with operations or else they have some competency issues that seem to call into question much of their other "brave new company" agitprop.
That's an interesting data point to keep in mind. Because KVM is boasting better efficiency than Xen, and Xen boasts ~2% overhead. Well, that might be theory...
Virtualization overhead numbers are basically useless since they depend on hardware generation, virtualization mode, configuration, workload, etc. Unless you're running exactly the same configuration as 37s, your mileage will vary... a lot.
