History

ZFS was originally developed by Sun Microsystems for the Solaris operating system. The source code for ZFS was released under the CDDL as part of the OpenSolaris operating system, and was subsequently ported to other platforms.

The illumos project was founded as an open source fork of OpenSolaris.

OpenZFS is the truly open source successor to the ZFS project. Development thrives as a part of illumos, which has added many features and performance improvements. New OpenZFS features and fixes are regularly pulled in from illumos, to all ports to other platforms, and vice versa.

Milestones

 * 2001 – Development of ZFS started with two engineers at Sun Microsystems.
 * 2005 – Source code was released as part of OpenSolaris.
 * 2006 – Development of FUSE port for Linux started.
 * 2007 – Apple started porting ZFS to Mac OS X.
 * 2008 – A port to FreeBSD was released as part of FreeBSD 7.0.
 * 2008 – Development of a native Linux port started.
 * 2009 – Apple's ZFS project closed. The MacZFS project continued to develop the code.
 * 2010 – OpenSolaris was discontinued, the last release was forked. Further development of ZFS on Solaris was no longer open source.
 * 2010 – illumos was founded as the truly open source successor to OpenSolaris. Development of ZFS continued in the open. Ports of ZFS to other platforms continued porting upstream changes from illumos.
 * 2012 – Feature flags were introduced to replace legacy on-disk version numbers, enabling easier distributed evolution of the ZFS on-disk format to support new features.
 * 2013 – Alongside the stable version of MacZFS, ZFS-OSX used ZFS on Linux as a basis for the next generation of MacZFS.
 * 2013 – The first stable release of ZFS on Linux.
 * 2013 – Official announcement of the OpenZFS project.

Effects of the fork (2010 to date)
OpenZFS-oriented developments have been completely separate from ZFS in Oracle Solaris.

As Oracle's code is not open source, the OpenZFS wish to maintain compatibility with Solaris ZFS pool versions 29–35 is difficult to realise.