Via TuxRadar, “OpenSolaris vs Linux“:
Linux has no ZFS support in the kernel because the Free Software Foundation doesn’t consider it free enough to be bundled with GPL software,[…]
ZFS is one of the more interesting developments in the *NIX world in this first decade of the 21st century. While efforts like the Linux ext4fs filesystem directly address very practical problems with its predecessors, ZFS instead tries to build an entirely new – and better – way of organizing storage. It’s hard to imagine any incentive for volunteers to invest the resources required to build something like ZFS from the ground up. Instead, continuing the previous thought,
… in Linux you have to mount the ZFS filesystem with Fuse as a filesystem in userland.
This sort of also-ran treatment of such a significant new technology seems to be representative of the status quo for Linux; that is, to see innovation and emulate, rather than to actually innovate. This will need to change at a fundamental level before Linux can be taken seriously.