Startup Ten's Complement LLC will bring ZFS to Mac OS X, its principal software engineer announced late last week. Offered as Z-410 Storage, the file system (and now an actual product) is in the process of beta testing.

The company's website says it started testing recently:

Essential OS Upgrades We're not quite there yet — but we have some exciting products in development. Our version of ZFS for Mac OS X, Z-410 Storage, started external beta testing last week. Expect more announcements soon.

Ten's Complement Software Architect is Don Brady, a former senior Apple engineer. In a series of tweets earlier in the month, he said the

# We finally got the installer package, disk image and beta website going! Once we confirm the process works we'll throw the switch... # We finished our bake-time testing. Once we wrap up release notes, SW license, installer and beta web site we'll be good to go...

In 2006, the next-gen file system developed by Sun was ported to Mac OS X. It was offered through an open source project. Many Mac storage and server managers expected expanded ZFS support to continue in Mac OS X Snow Leopard Server, however in the summer of 2009 Apple dropped the project altogether.

There were technical concerns. However, a number of sources said that Apple pulled the plug because of Sun licensing demands. And then there was worry brought on by the NetApp lawsuit.

ZDNet's Robin Harris ran down the issues in a post at the time:

The NetApp lawsuit may have come into play, making patent risk pertinent and potentially costly. Given that and the other CDDL-related risks, plus engineering opposition to GPL, Apple must have reluctantly stepped away. Apple would like bragging rights over Windows 7 that ZFS would give it, but in this narrative Sun’s pre-acquisition turmoil and tougher-than-expected licensing terms killed the deal.

Harris predicted that ZFS might return. And here it almost is.