Be aware of this if you currently use ZFS or are considering it. As of Kernel 5.0 it's not going to be given the time of day by the kernel maintainers. It's to do with Oracle not releasing ZFS to GPL. ZoL developers are trying to sort a workaround to keep their forked ZFS working with kernel 5.0. How it actually performs with the new kernel as a result of these changes is another matter. Details of the 'fix' and what the restrictions are can be found on Phoronix or the GitHub link for zfs below:
I may be misinterpreting this but it seems a lot like ZFS is dead in the water from this point forwards now unless you stick to LTS kernels with proper ZFS support or run BSD instead of Linux.