If memory-optimised tables always live in RAM, how do they survive a server reboot?

I clearly have a missing piece in my understanding of in-memory OLTP. Suppose that I have a memory-optimised table that is set up to persist both schema and data. Given that these tables always live in RAM, how does their data survive a server reboot? I've looked over the documentation, but I cannot recall seeing any mention of how or when their data is moved to disk. Indeed, as far as I know, the whole point of hekaton is that they don't live on the disk. Have I simply missed a piece of documentation?