> OpenZFS contains enough code not authored by Sun/Oracle that relicensing it now is effectively impossible. I don't think so. Suppose Oracle did agree to put

> OpenZFS contains enough code not authored by Sun/Oracle that relicensing it now is effectively impossible. I don't think so. Suppose Oracle did agree to put their code under GPLv2/CDDL dual licensing. Then, I'm sure if you look at the non-Oracle contributors to OpenZFS, there's a few big ones and a long tail of smaller ones. Many of the big ones might be able and willing to follow Oracle's lead. Chasing down the smaller ones may be harder, but it is possible their contributions may be judged as sufficiently trivial to escape copyright protection. More substantive contributions from people who are unreachable (or unwilling/unable to consent to the relicensing) can pose a bigger issue, but it could be solved either by (a) intentionally rewriting their contributions from scratch; (b) given enough time, decent chance (a) will happen anyway just to normal code churn, even if you don't do it intentionally for licensing reasons. It would be a big, multi-year project, but one that other open source communities have successfully tackled, most notably LLVM – so I do think "effectively impossible" is too strong. I think the biggest blocker is that, it is hard to motivate people to make the effort unless Oracle is on-board – and they've displayed no signs of willingness to change their position on this. I doubt Oracle will budge, but anything is possible. Another possibility to consider – CDDL clause 4 allows the "license steward" (Sun Microsystems) [0] to release a new version, which automatically applies to all CDDL software unless the developers explicitly opt-out. I don't know if any of the OpenZFS developers have made such an explicit opt-out – but if they haven't, then Oracle could issue a new CDDL version adding a clause saying that if the covered work is ZFS or a derivative thereof, anyone is allowed to relicense it under GPLv2. Then you wouldn't even need to track down and get the consent of non-Oracle contributors. For a real historical example of something like this, witness how the FSF issued a new GFDL version just to help Wikipedia move from GFDL to Creative Commons licensing. But, again, even if this is legally possible, unlikely (but not impossible) Oracle will ever cooperate in it. Another blocker is that even if OpenZFS were relicensed as GPLv2/CDDL, that still wouldn't solve the issue that Torvalds is unlikely to agree to upstreaming it as part of the mainline Linux kernel – a massive code base written in a very different style, and having portability concerns (wanting to work on BSD/etc too) which Linux normally doesn't care about. Possibly if you forked OpenZFS, ripped out the cross-platform aspects, and rewrote it to be more like typical Linux kernel code, it might have a chance. But, will anyone be willing to make that massive investment of time and effort? And even assuming they succeeded, we'd now have two forks of ZFS (one in the Linux kernel, one for other operating systems), adding to the maintenance burden, and the risk they'd diverge over time would be high. [0] Sun Microsystems still legally exists on paper, and probably will indefinitely, as an Oracle subsidiary – it has been renamed to Oracle America Inc – so Oracle has effectively inherited Sun's rights as CDDL license steward