By Daniel Eran Dilger

Published: 05:15 PM EST

Apple's efforts to support the development of ZFS, an advanced file system originally created by Sun, were officially terminated today in a notice posted by MacOS Forge.

The tersely worded message only stated that "The ZFS project has been discontinued. The mailing list and repository will also be removed shortly."

Mac OS Forge describes itself as "dedicated to supporting the developer community surrounding open source components specific to Mac OS X." It publishes source code and an information repository about a variety of open projects Apple funds and maintains, including:

• Darwin Calendar Server (used in iCal Server)
• Darwin Streaming Server (used in QuickTime Streaming Server)
• libdispatch (used in Grand Central Dispatch)
• WebKit (Used in Safari)
• XQuartz (used in Apple's X11 offering)
• and until recently, ZFS.

ZFS mania

Apple's interest in porting ZFS was first signaled in early 2006 when it contacted Sun's OpenSolaris project; By August 2007 an early, read-only port of ZFS was published on Mac OS Forge and command line support was added to Mac OS X Leopard.

Comments by Sun executives had tipped of wild speculation that ZFS would become the default file system of Mac OS X, and pundits pounced upon the idea that Apple's own technology was terrible and that anything it could replace with from outside sources would solve lots of problems for end users. The reality was that Mac OS X and third party software has lots of dependancies upon HFS+, and that ZFS really offered the greatest potential for server users. Most home Mac users don't even have multiple hard drives to pool with ZFS.

In February of this year, AppleInsider reported on Apple's internal efforts to add new read/write ZFS features to Mac OS X Snow Leopard Server and support these in Disk Admin's graphical user interface. The new feature was also being publicly promoted in the company's marketing of Snow Leopard Server.

By June however, Apple had scrubbed all mention of ZFS from its website and the feature disappeared from developer builds.

Stick a fork in it

Behind Apple's backtracking on ZFS is Oracle's announcement in April 2009 to buy Sun. While this should have no impact on other Sun technologies Apple has borrowed from OpenSolaris, such as DTrace, or other open source packages maintained by Sun under the GPL, such as MySQL, Sun's ownership and stewardship of ZFS is at risk because Oracle already has its own advanced, open source file system: BTRFS.

In addition to Oracle's unlikely desire to fund the ongoing development of two overlapping new file systems, Sun's ZFS had already come under fire for patent infringement from NetApp as part of a patent war instigated by Sun.

NetApp reported that ZFS not only infringes its WAFL storage patents, but that Sun intentionally designed ZFS to provide features unique to NetApp's WAFL, which Sun itself described it its marketing as "the first commercial file system to use the copy-on-write tree of blocks approach to file system consistency."

This leaves Apple with an unfinished, patent-encumbered file system and without an enterprise class partner to work with in developing the future of ZFS. Were Apple to develop ZFS on its own, the technology would likely be relegated to pariah status by the rest of the industry.

It remains to be seen whether Apple will begin working with Oracle to port the similar BTRFS to Mac OS X, or simply continue to add new features to HFS+ while monitoring the landscape for promising new file system options. In any case, ZFS appears to be very dead.



Daniel Eran Dilger is the author of "Snow Leopard Server (Developer Reference)," a new book from Wiley available now for pre-order. The book edited out all mention of ZFS.