I tried re-installing (the good old) Windows Home Server 2011 on a 120GB SSD, but it was too small to meet the OS requirements, even though WHS 2011 only uses approx. 60 GB of HDD space. I found a simple way to get around this
After trying multiple ways to alter configuration files to avoid the check, but they all failed to finish the install. I found one that was very simple, and worked perfectly.
Boot of a USB/DVD as normal, and wait until you are greeted with the “Install/Repair” screen. Press “Shift+F10” to open CMD.
From here you can write “notepad.exe” (without the quotes), and then open the file: “sources/SKU/SERVERHOMEPREMIUM.def” (remember you might have slightly different name on your Windows version).
This is the file that defines the requirements for the installation program. Alter the HDD space/RAM or whatever is stopping you from completing the installation, and save and close notepad.
Write “wpshell.exe” after closing notepad, and hit enter. The installation wizard should now restart, but with the temporarily edited definition file, allowing you to install without any restrictions.