I don't think GPL is necessary, but it's difficult to see the project gaining too much widespread support if it can't be included upstream in linux. It will just be for those people comfortable with deeply modifying their own OS away from distro defaults, which is a fairly small segment of the overall userbase. Although I'm not sure ZFS is even particularly interested in supporting random desktop users, so maybe they don't view that as a problem.
I've read the rhetoric on how great ZOL is and all that, but trusting something as important as the filesystem implementation to out-of-tree patches just seems fundamentally wrong. I would very much like to see this re-licensed under a GPL-compatible license.
I use a parity RAID scheme for redundancy, but I don't have true back-up media. I'm not gonna fuck around with out-of-tree filesystems.
So X and Wayland according to you are not free, also many lines of code in the Linux kernel that are BSD licensed. If you don't like those "unfree" licenses feel free to remove those software and code, look how free you are without them.
In the meantime people in the real world would be happy with BSD licensed ZFS.
What is the status of the various ZFS pool versions? Is there only a split now between Oracle Solaris and the rest of the open implementations (FreeBSD, Linux, Illumos, etc.)? Or are all the open implementations fragmented as well?
It's quite unlikely that ZFS will make it into any of my machines. I normaly have no problem with out of tree patches. But they can be removed at any time when upgrading to a new kernel. If I want a new kernel version and patches like BFS or BFQ haven't been rebased yet, that's no problem. The system will work without them. But once a patch is not optional and your data is in a ZFS filesystem, then you're locked in. Filesystems really need to be in the upstream kernel or use FUSE.