Ivy Bridge and even Sandy Bridge are still in production at GCE. These things are economically viable long after the (very misguided, extremely outdated) traditional thinking of recycling hardware after 3 years.
IIRC clock for clock even the latest Intel CPUs are only 30-40% faster than Ivy Bridge at best and hover around 20% faster on average. So I don't find it that surprising GCE (or AWS) keeps SB and IB machines around. I imagine VMs on the lower power tiers are far more popular than high power tiers so those older machines still end up with full utilization.
I think the popularity of the ancient machine families on both GCE and EC2 is due to inertia and copypasta and ignorance. People write down "m4.large" and just leave it that way until it stops working. The GCE N1 family that contains SNB and IVB is slower but not cheaper.
That's a good point. I was thinking more about from GCE/AWS side, they'll keep these old machines running because they can shuffle off low priority/power loads to them. But it makes sense from the customer side they're just configuring by rote rather than looking for the best price-performance.
