ZFS was developed by Sun Microsystems for the Solaris operating system, not FreeBSD. The original and currently developed ZFS branch is still closed source and developed by Oracle who acquired Sun nearly a decade ago. It has diverged quite a bit from the project that was open-sourced for OpenSolaris around 2009, which is a fork of the original closed-source ZFS that has been ported to any other OS. The project is called OpenZFS, and the project that diverged from that for adaptation to Linux OS is called ZFS on Linux (or ZOL).
FreeBSD just had one of the first development teams that recognized the significance of OpenZFS fork and jumped to port it to their OS when OpenZFS was released under the CDDL. BSD also is released under the BSD license, which is more compatible with CDDL since you can essentially do anything you want with software released under BSD license, unlike GNU, which requires that software released under GNU license remain free and open-source (for example, Apple Darwin is a fork of BSD which has been made closed-source and is now sold for profit).
Here's more about why GNU licenses and CDDL licenses are supposedly incompatible (I don't really see it, personally, but it's apparently a big argument): https://www.whitesourcesoftware.com/whitesource-blog/top-10-cddl-license-questions-answered/ )
I think what it's basically saying is if you distribute something under GNU you can't release portions of it under CDDL, but if you have something that's CDDL it has to remain CDDL so it can't be included under GNU.
At the end of the day, I don't think anyone really cares other than lawyers or developers, and when software is free there's not a lot of desire to get involved in lawsuits, so let's start bucking the trend and distributing copies that are easier for people to start using this technology. I'm neither, and I imagine I'm not alone that all this licensing stuff makes my eyes glaze over when I just want the best-working system technologies. ZFS is hands-down the best file-system / raid / memory caching software I've ever used and once you get it in there, it's dead-simple to use.
I used a wrapper from this github site to make an ArchISO install disk that worked fine: https://github.com/stevleibelt/arch-linux-live-cd-iso-with-zfs
you need to add this repo to your /etc/pacman.conf file:
Maintainer: Jesus Alvarez (demizer)
Description: Packages for ZFS on Arch Linux.
Upstream page: https://github.com/archzfs/archzfs
Server = http://archzfs.com/$repo/x86_64
from here: https://wiki.archlinux.org/index.php/unofficial_user_repositories#archzfs and here: https://wiki.archlinux.org/index.php/unofficial_user_repositories#archzfs
I had to put
SigLevel = Never under the [archzfs] line because I had problems importing this repo's key using
pacman-key -r (feel free to correct me if I did that wrong).
More about pacman here: https://wiki.archlinux.org/index.php/Pacman/Package_signing
I kind of recommend people start out just having secondary storage with ZFS and not use ZFS for root though. Although it's cool to have ZFS-style snapshots for OS configuration changes and the memory caching, etc. you can at least do the snapshots with BTRFS for your root and it's a lot easier to get working properly.
Re: File system stability, I've never had any issues with BTRFS, I think it's perfectly fine for any general end user, it's when you get into enterprise stuff it gets called into question... A lot of the reasons for its reputation of corrupting files, etc. have been dealt with, it's just still fresh in people's minds because its only 6-7 years old. Conversely, I've had no issues with stability with ZFS on Linux once I get up and running, it's just really hard to get it on the root filesystem. It's dead-easy for FreeBSD because they build it into the installer, but BSD's userland is kind of ■■■■■■ compared to Linux. So the struggle continues.
Even using this wrapped archISO with zfs, when I was trying to set up the root partition I managed to ■■■■■ my grub following the same guide I used for zroot CentOS on GitHub (I think part of it was just that I was tired...). For some reason I am just driven by trying to get this stuff right even though it doesn't really serve any real purpose other than self-aggrandizement and sense of achievement, and after 2-3 days (literally) of struggling to get working, I am starting to really question if its worth it... Maybe it'll be easier for someone else...
Here's the guide for CentOS ZFS on root: https://github.com/zfsonlinux/pkg-zfs/wiki/HOWTO-install-EL7-(CentOS-RHEL)-to-a-Native-ZFS-Root-Filesystem
But the Debian/Ubuntu one is probably more up to date (I just had already done the CentOS one so I wanted something I was familiar with) https://github.com/zfsonlinux/zfs/wiki/Ubuntu-16.04-Root-on-ZFS
Someone take over for me. I'm going back to sleep...