What operating systems can use RAID-Z?
ZFS, and therefore RAID-Z, are included in Solaris by default, as well as in the open source OpenSolaris. They are also available as an add-on in FreeBSD, and can be installed, with some effort, on Linux via Fuse. The ZFS licence clashes with the GPL licence used by Linux, so at present, ZFS can’t be distributed with Linux, but it is possible for experienced users to install it themselves.