OpenZFS is an open-source implementation of the ZFS file system and volume manager initially developed by Sun Microsystems for the Solaris operating system and now maintained by the OpenZFS Project. It supports features like data compression, data deduplication, copy-on-write clones, snapshots, and RAID-Z. It also supports the creation of virtual devices, which allows for the creation of file systems that span multiple disks.
One of the unique features of OpenZFS is its self-healing capabilities. The file system can detect and correct errors on the fly, without the need for a dedicated file system checker, which means it can be used in mission-critical applications requiring high availability.
OpenZFS is widely used in enterprise and data center environments, as well as in consumer devices like network-attached storage (NAS) devices. It is available for many operating systems, including Linux, FreeBSD, macOS, and Windows (through third-party solutions). OpenZFS is licensed under the CDDL (Common Development and Distribution License), which allows for both open-source and commercial use.
Founding members of OpenZFS include Matt Ahrens, one of the main architects of ZFS. , OpenZFS (on some platforms such as FreeBSD) is gradually being pivoted to be based upon ZFS on Linux, which has developed faster than other variants of OpenZFS and contains new features not yet ported to those other versions. The merged code-base will include a number of new features, performance enhancements, and is proposed to be known as OpenZFS 2.0.
History
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.
The following is a list of key events to the development of ZFS and its various implementations, leading to the creation of OpenZFS as an umbrella project:
2001: Closed-source development of ZFS started with two engineers at Sun Microsystems. 2005: ZFS source code was released as part of OpenSolaris. 2006: Development of a FUSE ZFS port for Linux started. 2007: Apple started porting of ZFS to Mac OS X. 2008: A port to FreeBSD was released as part of FreeBSD 7.0. 2008: Development of a native ZFS Linux port started, known as ZFS on Linux. 2009: Apple's ZFS project closed, and the MacZFS project continued to develop the code. 2010: OpenSolaris was discontinued, resulting in the further development of ZFS on Solaris being no longer open-source. 2010: illumos was forked from OpenSolaris as its open-source successor, and continued to develop ZFS in the open. Ports of ZFS to other platforms continued pulling in 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: Coexisting with the stable version of MacZFS, its prototype generation (known as OpenZFS on OS X or O3X) uses ZFS on Linux as the new upstream codebase. 2013: The first stable release of ZFS on Linux. 2013: Official announcement of the OpenZFS as an umbrella project. New features and fixes are regularly pulled into OpenZFS from illumos and pushed into all ports to other platforms, and vice versa. 2016: Ubuntu 16.04 includes the open-source ZFS file system variant by default.
Ported versions (2005–2010) 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 user-space, 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.