We have onpremise Dynamics 365 CRM installation where we have from time to time heavy load on various workflow runs. 

What can we do in order to have "when needed / on-demand" more backend server azure capacity. I know we can upgrade serveers with more cpu and memory and then ramp them down when not needed.

BUT is there a way to ramp up backend servers when needed: Can we just install eg. 10 backend servers and then shutdown 5 of them when not needed. Will Dynamics handle situation when some of it's servers are down - and can it take new servers back "on the fly" ?