I've put together a new How-To for NFS-RAMBOOT - a boot script hack to load the entire OS partition into RAM. The result is like a very fast SSD.

In this version, the OS is copied over from a file tree instead of a compressed tarball. This means longer boot times, but rsync is able to do a very fast incremental update at any time. The update is so fast and efficient that you can run it in a continuous loop every few seconds.

With continuous sychronization, it's kind of like a RAID1 mirror where the "primary" copy is a super fast RAM disk and the "backup" copy is a much slower SSD or hard drive.

http://www.linuxquestions.org/questi...ization-37498/

This how-to is for Debian 9, but it'll work on other distributions. The fundamental init script hack is unchanged from before Debian switched to systemd.