Dual boot separate shared partition vs shared home partition

Question

I want to make a comfy dual boot of windows and linux (arch I guess) so their downloads, documents etc. are the same. I think that would be quite convenient. And I'd like to use a separate home partition on linux to be able to change distro more easily. So, I have come up with these two ideas:

1. Windows partition, Linux core partitions (system/swap), Linux home partition and link windows user home folder to this partition as well, so there are both files from windows home folder and linux one, but I worry that something might come up in the future like compatibility issues or being unable to separate these two (though right now I don't think I would need to do that)
2. Windows partition, Linux core partitions, Linux home partition, shared partition, and make links to some specific folders here from both OS-es (like specifically downloads documents etc.) but the home directories themselves are on their own partitions

so in 1. case if I create a file let's say at ~/file.txt on either of OS-es, it will automatically be accessible from both, whereas if I do that in 2. case, it will just be in its own partition

what advantages or drawbacks do you see and do you think one of these is more preferable than the other and why?

Answer 1

It would be possible with Linux accessing the Windows home directory on NTFS (especially using the newer ntfs3 Linux driver – it's a bit more troublesome with the older NTFS-3g), but I would be worried about conflicts between programs on the two systems. Primarily when a cross-platform app uses the same path on both Linux and Windows (OpenSSH with ~/.ssh/config being one specific example), yet expects that file to contain different settings for each platform, e.g. refer to different file paths on each system.

For example, my own ~/.ssh/config needs to set PKCS11Provider to C:/Something/libykcs11.dll on Windows but /usr/lib/something/libykcs11.so on Linux; sharing the home directory would make that impossible.

So I would not recommend doing this for the entire home directory. Instead, link just the specific subdirectories such as Desktop or Music, or create a separate NTFS volume for sharing.

Also, while that AskUbuntu post is correct, it should be emphasized that NTFS-3g attempts to translate permissions between Windows and Linux, which can end up being an unreliable mess in some situations. The new "ntfs3" Linux driver takes a different approach – it stores Linux permissions in dedicated attributes, keeping them isolated from the Windows ones, so that each OS can do its own thing.

Answer 2

Is it a bad idea to create a home partition in ntfs or fat and also store windows files there? Does linux work with them much worse than with ext?

Yes, it is avery bad idea. That you can do something doesn't mean you should.

I'd like to use a separate home partition on linux to be able to change distro more easily

Not even this is recommended. It's true that traditionally it has been deemed "safe" and even suggested precisely because of the reason expressed above.

However, users must understand /home stores settings as well, not just user files and preferences. Often the settings aren't at all compatible between distros especially with very different Desktop Environments. So, the perceived "time saving" feature for distro hopping often ends up being counterproductive.

Over the years Linux distros have became more complex and most of it stems from the DEs being used. The old settings more often than not will interfere with the new distro's DE and frequently prevents it from booting correctly. Even when the "old" distro is Ubuntu and the "new" is an Ubuntu derivative like Linux Mint or the other way around, problems can and do happen (standard, "vanilla" Ubuntu runs Gnome and standard Mint runs Cinnamon; settings from the former do not play well with the latter and vice-versa).

The recommended practice nowadays is:

1. Simplify, do not "over-partition". For many distros not even a separated swap partition is needed because their default is to use a swapfile instead. Don't create a separated /home because it seldom has advantages.
2. Have proper backups, always! Don't be lazy and take the separated /home as replacement for proper backups. It isn't and never will be.
3. Have a separated DATA partition which isn't and won't ever replace /home when dual-booting and if you need to shared files between OSes. And if dual-booting with Windows then disabling its Fast Startup feature is a must. Make sure to create the additional shared partition with a filesystem supported by both OSes accessing it (NTFS is recommended in this scenario; exFAT can be a choice if the Linux side supports it correctly).