In June, we noted that Sun's ZFS file system, previously mentioned by Apple as being included in Mac OS X Server Snow Leopard, had been removed from Apple's documentation for the release. The change was ultimately reflected in the released version of Snow Leopard, which does in fact lack support for ZFS.

MacRumors had heard that the removal of support for ZFS, which had even made appearances in Leopard, from Snow Leopard was due to licensing issues, and a recent posting from data storage expert Robin Harris suggests that this may indeed be the case.

But then a couple of sources came in with a new angle: that Sun's licensing demands killed the deal. Sun prefers the CDDL [Common Development and Distribution License] and may have asked for some extra protections, including patent indemnification, that caused Apple to reconsider the business risk of ZFS.

While Sun could elect to release ZFS under a GNU General Public License (GPL) that would enable inclusion of support for it in other settings, the company has yet to do so. Harris notes, however, that Oracle's pending acquisition of Sun could open the door to reconsideration of ZFS licensing issues.

Now that Oracle is acquiring Sun things look brighter. Oracle is already bankrolling a GPL'd ZFS clone - btrfs - that will take years to reach the level of maturity that ZFS now enjoys. Once they own ZFS why wouldn't they GPL it and call it good?

In Harris' view, Sun's apparent reluctance to license ZFS represents a significant missed opportunity for the company and the industry, one which Harris hopes can be rectified in the near future.

The ZFS team has produced a game-changing file system/volume manager. The chance to get it into the hands of 10s of millions of Mac users - and to influence Redmond's file system strategy - seem to this outsider an opportunity of a lifetime.

If the ZFS engineering team opposed this - and I'd love to hear their take - I encourage them to reconsider. Marketers often ask the question "would you prefer 100% of nothing or 40% of something huge?"