this sounds interesting; first time I've heard of this. Any reason to this? Isn't it quite a few steps to have to enter BIOS & change profile every time you want to switch the OS?
Suppose you want to install 3 different windows OS, and you have three different sata SSDs which are formatted. If I don't disable any SSD in bios
(a.k.a disabling sata port only) and start installing windows on
SSD A, what will happen is it will install
bootloader + windows on
SSD A, now if I begin to install windows again on
SSD B, what will happen is it will install only
windows and add it's entry into
bootloader on
SSD A, similarly when I install windows on
SSD C, it will install only
windows and add it's entry into the
bootloader on
SSD A.
So when we install windows it first detects if there is a bootloader on any storage device, if not found, then it will install bootloader with windows.
Up until now I have setup like this.
SSD A - Bootloader + windows
SSD B - windows only
SSD C - windows only
If anything happens to
SSD A, then windows on
SSD B and
SSD C will not be able to boot, because there is no bootloader on system. Also if you want to install
clean windows again on
SSD A for some reason the previous bootloader will get wiped and with it the entries for windows on
SSD B and
SSD C will also get wiped, so they won't be able to boot.
So solution to this problem is :-
Before installing windows disable other drives where you want a different operating system to be installed and also disable drives where an operating system already exists. This way the installation will not find any bootloader nilly willy and it will always install
bootloader + windows on the selected storage drive.
With this setup you will always end up with
SSD A - Bootloader + windows
SSD B - Bootloader + windows
SSD C - Bootloader + windows
This is where complete isolation between operating system is achieved, no matter what happens to any OS, your other OS's will always work. You don't give any particular bootloader all the power to manage all your operating systems, instead you go one step lower and handle boot selection in the BIOS itself manually.
Yes it involves more steps to select your operating system, but BIOS have profile options which are easy to switch, you pre populate your profiles with only one boot drive enabled, along with it you can enable those drives
(which don't have any operating system, just have data) which you want to show up in all your operating systems, or maybe you want some drives to show up only on certain operating systems, you get complete control.
You decide in your BIOS that which operating system will get access to what storage drives.
This example is targeting windows OS's but you can also mix other operating systems there is no difference.
The only requirement is 1 sata drive per operating system and you are good to go. This also frees you from partitions and their types.
This method is my own, it's nowhere on the internet I believe.