We 've been discussing the ZFS file system in Linux for some time now . In fact, Richard Stallman himself said that "Including ZFS in Linux was impossible " due to licensing incompatibilities between the GPL and CDDL. But Canonical has also been working on it for a while because of the benefits this file system offers for their Ubuntu distribution. In fact, they've now implemented ZFS support on the root partition as an experimental option in their Ubuntu 19.10 installer.
Ubuntu 19.10 "Eoan Ermine" will bring significant improvements , making it one of the biggest updates to the popular Linux distribution. Canonical has some surprises in store, as well as new features, before the arrival of Ubuntu 20.04 LTS. Among them is the ZFS feature I mentioned, which allows you to format your root partition if you wish. This way, you'll have access to all the power and advantages it offers.
For those unfamiliar with ZFS , it's a file system whose acronym stands for Zettabyte File System. It was originally created by Sun Microsystems (now Oracle) for their Solaris operating system. Since 2004, the project, led by Jeff Bonwick, has continued to grow and evolve. It's notable for its capacity, management methods, self-healing, copy-on-write transaction model, snapshot support, dynamic striping, variable-size blocks, transparent encryption, and more.
Regarding the licensing issue, Canonical did it this way because zfs.ko, the kernel module with the driver for this file system, is independent of the Linux kernel and can therefore use a non-GPL license. That's the way it is; in fact, Linux modules were created precisely for this purpose: to allow modules with other licenses, and even closed-source modules, to be integrated without conflicts with the GPL. Personally, I think having ZFS in Linux isn't negative at all; quite the opposite.
Incidentally, there is also a fork of the original ZFS known as openZFS.