What powers Etsy

I think there are certainly specific web and db loads that aren't going to work as well under VM scenarios, but on the whole our experience has been positive. There will, I imagine, always be a slight 'slowdown' due to VM but with the gigantic push toward 'the cloud' right now, it seems to me one of the last things on the minds of most (and obviously Xen is highly used in that field, which is also what we use).

The bigger question I think is if you are using a highly CPU bound task which VM isn't always very good at. According to Etsy they are very CPU bound, so it makes some amount of sense.

I think the performance hit for many people is overstated. Unless you're at the long-tail of CPU bound instances I imagine it won't become very apparent. That said, if I'm missing something/incorrect then someone please correct me!

I should also say it's a bit heartening to know of other e-com groups out there benefiting from an in-house stack rather than attempting to go 'TO THE CLOUD!'.

One example where virtualization is easier in practice is where you're not in control of the network intfrastructure -- ie: you subcontract management of switches etc to someone else.

For someone the size of Etsy that wouldn't matter much -- they have an obvious need to manage the entire stack. But for smaller institutions that might not target "scaling up to serve the entire public web" -- it is a factor.

Another example is if you have heterogeneous hardware -- it is much easier to just install a hypervisor that runs on every box and then manage that via your vm-toolset, that set up many different images. It also makes it easier if you need to run different os' -- do all your os images have drivers for all your hardware?

Granted, in theory OS' should abstract away hardware -- in practice, if you need to change out a few of your mysql instances running GNU/Linux to Microsoft SQL servers for a new project/change in workload -- being able to just spin down the old vms and up the new ones helps a lot in terms of agility.

But yes, it's absolutely possible to provision physical hardware as well.

Sure. Premature optimization and all.

Huh. SSD from a major chip vendor perhaps? I had one of those bite me just a few weeks ago. in my case it would have been fine if the drive offlined itself. but the intermittent io pauses killed performance, but not health checks. Actually, same type of problem RO FSs make me scared of.