Running Alpine from RAM, installed to hard drive

Hello,

I'm new to Alpine. Perhaps you could clear a few things up for me?
I want to install Alpine to my hard drive, and run it from RAM. (So that it ran fast and didn't needlessly touch the harddrive.) I've got more than enough RAM to handle it.
I gather the way this works, is first, important system binaries in the harddrive are copied to RAM, and then the binaries are run from the RAM, only referencing the hard drive when opening some new data file.

From what I have seen in the installation instructions, there are three ways to install Alpine Linux:
1. Diskless mode. It seems this only works for removable medium, not a hard drive. And the way you save changes is by choosing some other medium to write to "Alpine Local Backup (lbu)". I don't understand, does this boot to RAM, or it always reads from the removable medium?
2. Data mode. Seems very similar to diskless mode, except with a more permanent place to save data. I still don't understand, does this boot to RAM?
3. Sys mode. This writes the system to the hard drive - which is what I want. But I still don't understand, will Alpine be booting into RAM?

Thank you.