I am currently running windows on one of the M.2 drives. I want to switch everything over to Linux. I want to have Fedora on the main M.2 drive as my daily driver. I also want the second M.2 drive to have multiple partitions for other Linux distros. The 2 TB ssd is going to be for /home.
Couple of questions:
What is the best way to partition it? /boot directory on main M.2? /swap on main M.2?
Here is a bigger problems. I currently have my 2 TB drive partitioned with multiple Linux partitions sharing the /home, which is both a great benefit and also problematic. It is great that I can login to a new, or different, Linux distro and have all my stuff already configured. But, when running multiple KDE instances, it screws up icons and even the application launcher with what application are available since every distros uses their own application app stores, etc.
This is the global view of what I want to do, just trying to get around some of the technical issues.
The users home directory contains individual configs for each user and the specific apps that are installed and used on each distro.
Sharing the users home directory then becomes problematic as you already noted.
Instead, create a separate data partition that may be mounted as a subdirectory of the users home directory and share that data partition without sharing the actual home directory. This should avoid the conflicts you have already seen.
I would envision this structure for the 2TB drive.
Each OS could have /home/USER within the installed base on either M.2 drive and simply mount the data partition at /home/USER/data with the data partition residing on the SSD. The only requirement then would be that the UID for each user be the same so that when mounted all the files in the data partition belong to that user.
I would install the daily driver on the main M.2 drive as you indicated. This would (probably) use uefi for booting.
You then remove the partitions on the second drive that are related to that OS. Then for each additional OS in use install it on the second drive and don’t allow shared use of the efi partition on the main drive (some distros use an identical named /boot/efi/EFI/ubuntu directory for their efi config so each may require its own efi partition). Create separate efi partitions for each OS installed.
Then grub would need to be updated on fedora (which I assume would be the daily driver) so it could identify and properly boot each additional OS.
Note also that with multiple linux OSes, the last OS to update grub may take full control of booting so you would need to be prepared to recover the daily driver control of booting.
Just so I am clear, is creating a ‘data’ directory is the best way, or easy way, or…? What I am saying is, is there a way so make it so ‘Documents’ and ‘Pictures’ (etc.) on each distro point to ‘Documents’ and ‘Pictures’ (etc.) on the /home directory. Maybe by creating a symbolic link or something. I don’t really know what I am talking about per se so I hope that is making sense.
I wouldn’t mind creating links each time I install a new distro as long as it isn’t too much work, or complicated. I know it isn’t a big deal, but it makes me feel all warm and fuzzy inside to have my Documents in the actual Documents folder.
BTW: I don’t use GRUB. I found it to be a real hassle in dealing with multiple distros. So, I have been using rEFInd. It has be awesome. Right now I have 6 Linux distros installed and I haven’t had a problem yet. I have my bios boot loader load the boot partition that has rEFInd on it first and it has been great. One or two of the installed distros will load it’s GRUB after I have selected to boot that os. So, basically I get two boot menus in a row. Not a big deal, I just haven’t had the time to narrow down EXACTLY how/why those are doing that.
I really wish I could just run multiple kde’s without it conflicting. Like, I wish the KDE configs were in /usr that I wouldn’t copy over instead of ~/.config that does copy over. That would make life so much easier since that is really the problem.
You could create those directories on the DATA drive, then use symlinks for each user to access them.
Example.
The user home directory would be /home/USER with the data drive mounted at /home/USER/data.
the user should be able to remove /home/USER/Documents then replace it with a symlink to /home/USER/data/Documents with the command ln -s /home/USER/data/Documents /home/USER/Documents
The subdirectory in the /home/USER directory should be removed before creating the symlink.
Separating the users home directories as noted should avoid this issue since now the ~/.config tree would be unique for each installation.
& Welcome to 
