Google and Facebook don't bother with management modules; They're more likely on switched power for each machine, with significant work in automatic netboot reprovisioning when things go wrong on these systems. In the event that fails, they swap machines out for diagnosis... if they bother with the diagnosis part.

Ahh yes, the tried and true "turn it off and on again" philosophy...

All kidding aside, if it's a random rare issue (some bit flipped somewhere), chances are that power cycling it may fix the issue (upon initialization). If it's anything more serious, the issue will likely persist, in which case taking the machine out of production is likely the best immediate course of action.

AFAIK Facebook tried reboot-on-LAN for one generation then went back to BMCs. I haven't seen any explanation about why, though.

Facebook apparently is just getting to this recently:

https://code.facebook.com/posts/1471778586452119/openbmc-for...