OpenZFS

The OpenZFS is an umbrella project aimed at bringing together individuals and companies that use the ZFS file system and work on its improvements, aiming as well at making ZFS more widely used and developed in a true open-source manner.

OpenZFS brings together developers from the illumos, Linux, FreeBSD, and macOS platforms, and a wide range of companies. High-level goals of the project include raising awareness of the quality, utility and availability of open-source implementations of ZFS, encouraging open communication about ongoing efforts toward improving open-source variants of ZFS, and ensuring consistent reliability, functionality and performance of all distributions of ZFS.

Illumos, which is derived from OpenSolaris, provides upstream source code for other ZFS implementations. While there are various differences between the illumos ZFS codebase and other open-source implementations of ZFS, OpenZFS is strategically reducing existing platform-related differences in order to ease sharing of the source code.

Founding members of OpenZFS include Matt Ahrens, one of the main architects of ZFS.

The ZFS file system was originally developed by Sun Microsystems for the Solaris operating system. The ZFS source code was released in 2005 under the Common Development and Distribution License (CDDL) as part of the OpenSolaris operating system, and it was later ported to other operating systems and environments.

As the FSF claimed a CDDL and GPL legal incompatibility in 2005, Sun's implementation of the ZFS file system wasn't used as a basis for the development of a Linux kernel module, it wasn't merged into the Linux kernel mainline, and Linux distributions did not include it as a precompiled kernel module. As a workaround, FUSE, a framework that allows file systems to run in userspace, was used on Linux as a separation layer for which the licensing issues are not in effect, although with a set of its own issues that include performance penalty. However, the April 2016 release of Ubuntu 16.04 LTS includes CDDL-licensed ZFS on Linux as a kernel module that is maintained as a separate project, outside the Linux kernel mainline, claiming license compatibility.

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