Comment by MauritsVB

Oracle changing the license would not make a huge difference to OpenZFS.

Oracle only owns the copyright to the original Sun Microsystems code. It doesn’t apply to all ZFS implementations (probably not OracleZFS, perhaps not IllumosZFS) but in the specific case of OpenZFS the majority of the code is no longer Sun code.

Don’t forget that SunZFS was open sourced in 2005 before Oracle bought Sun Microsystems in 2009. Oracle have created their own closed source version of ZFS but outside some Oracle shops nobody uses it (some people say Oracle has stopped working on OracleZFS all together some time ago).

Considering the forks (first from Sun to the various open source implementations and later the fork from open source into Oracle's closed source version) were such a long time ago, there is not that much original code left. A lot of storage tech, or even entire storage concepts, did not exist when Sun open sourced ZFS. Various ZFS implementations developed their own support for TRIM, or Sequential Resilvering, or Zstd compression, or Persistent L2ARC, or Native ZFS Encryption, or Fusion Pools, or Allocation Classes, or dRAID, or RAIDZ expansion long after 2005. That's is why the majority of the code in OpenZFS 2 is from long after the fork from Sun code twenty years ago.

Modern OpenZFS contains new code contributions from Nexenta Systems, Delphix, Intel, iXsystems, Datto, Klara Systems and a whole bunch of other companies that have voluntarily offered their code when most of the non-Oracle ZFS implementations merged to become OpenZFS 2.0.

If you'd want to relicense OpenZFS you could get Oracle to agree for the bit under Sun copyright but for the majority of the code you'd have to get a dozen or so companies to agree to relicensing their contributions (probably not that hard) and many hundreds of individual contributors over two decades (a big task and probably not worth it).