Basically, this is a ZFS fork, forced by the stupidity of Oracle. The whole issue is that Oracle has stopped publishing the source code of new ZFS versions for

Basically, this is a ZFS fork, forced by the stupidity of Oracle. The whole issue is that Oracle has stopped publishing the source code of new ZFS versions for some years already: there are new ZFS "versions" (pool versions from version 29 to 34, which include some new backward-incompatible features) from Oracle, but no new open source code has been released. The opensource ZFS code has been almost stagnant/in mainteinance mode all this time. OpenZFS is an attempt to keep ZFS open source alive. Since Oracle doesn't work with opensource anymore, the people who uses ZFS (BSDs, Nexenta, etc) have to do their own thing, and evolve the filesystem in their own way..