Seriously. A person who would advocate using IPMI at scale has either never owned an IPMI card or has never worked at scale or both. The just don't work, and they erase whatever power savings you're trying to achieve.

Although... if you have the engineering resources of Facebook, you can write your own IPMI software and probably get it working pretty well. They're all just embedded ARM systems after all..

I ran out of motivation, but I did manage to fix up some of the SuperMicro IPMI firmware: https://github.com/devicenull/supermicro_ipmi_firmware

Real servers can't be bought without IPMI and AFAIK the BMC cannot be turned off, so it's probably not worth worrying about BMC power if there's nothing you can do about it.

Sure, but as you're aware facebook, google, et al don't buy "real servers", they buy servers that actually meet their requirements. That's why "real vendors" like HP have missed the boat on selling millions of servers into the cloud.

Speaking of Facebook specifically, the evolution is interesting. They replaced BMCs with the reboot-on-LAN hack but then their next motherboard version had BMCs again. It would be interesting to hear the story behind that.

I actually advocated using the vendor specific ones with the BMC being if you use shitty hardware. It works ok, but is absolutely suboptimal.