Don’t call Illumos a fork of OpenSolaris. When the project was officially announced today, Illumos was described as an attempt to fully open-source OpenSolaris by working alongside Oracle. And while Illumos is not a fork, the project is all about giving the community the power to fork.

In many ways, the fate of OpenSolaris mirrors that of Java. When Sun decided to create the OpenJDK, the first thing it had to do was replace the proprietary portions of Java code with open-source alternatives. For the OpenJDK, that meant writing new cryptography and font code. For OpenSolaris, it means writing a completely open-source libc, some new drivers and a new NFS lock manager.

The Illumos project was created by Garrett D’Amore, the senior director of engineering at Nexenta, an enterprise storage company. D’Amore said that the fundamental goal of the project is to give OpenSolaris users a choice rather than leaving the platform to wither on Oracle’s vines.

Oracle has declined to comment about Illumos or any potential partnership with the project.

D’Amore held a conference call today where he laid out the plans for Illumos. While he spoke, hundreds of interested developers and users joined #illumos on IRC, where they discussed the project. D’Amore frequently referenced this virtual gathering of hundreds as the critical mass that Illumos was looking for.

“The problem with the fact that not all of this source code is open is that it presents some challenges downstream for people who rely on OpenSolaris,” said D’Amore. “This problem is not new to the industry. Some years ago, Apple had done the community a great favor by opening their code in Darwin, but you can see the end result of that, the end result we would all like to avoid.”

Apple’s Darwin project has all but vanished after seeing a downturn in interest, and when Apple switched to Intel processors, which are not compatible with Darwin.

Simon Phipps, a former Sun employee who is a member of the governance board for the OpenJDK and for OpenSolaris, said that Illumos is a terrific project, and that he was happy to see the community forming to save OpenSolaris. At Sun, Phipps served as the company’s Chief Open Source Officer.

“I am very pleased you’re doing this Garret,” said Phipps in the conference call announcing the project. “When we started the OpenJDK, there was a concern that Sun wouldn’t get around to open-sourcing all the code, so some people created a project called IcedT. It was the existence of that project that made the OpenJDK be a completely free project. I’m looking at Illumos, and that’s exactly the right approach to take.”

Phipps then said that he would remain on the OpenSolaris governance board “for as long as we still have one.”

Another former Oracle and Sun employee who is excited about Illumos is Bryan Cantrill, one of the creators of DTrace. Cantrell recently left Oracle to join Ruby hosting firm Joyent, itself a  heavy user of both OpenSolaris and Solaris.

“This is terrific news,” said Cantrill on the conference call. “Looking back historically, Sun understood the importance of the right to fork the OS, but we underestimated the importance of the power to fork the OS. As we all know, Sun never made it to 100% open source. Sun didn’t do it by design, but it effectively did not allow for a fork.

“A fork is a really important check against an open-source project. It allows people to innovate. It allows people to not get hung up on governance models. It allows people to express their independence of a project. The community had the right but not the power. This is giving all of us in the community the power to fork the system. Not that we want to exercise that power.”

Illumos will eventually become a completely open-source implementation of OpenSolaris, said D’Amore, and will be licensed under the CDDL license, though BSD and MIT licenses will also be compatible. He said that the goal is to be completely compatible with existing Solaris operating system versions, so Illumos will be able to run binaries compiled on Solaris.

And though Oracle has long been rumored to be unconcerned and even hostile toward OpenSolaris, D’Amore pledges that Illumos will be built in collaboration with Oracle.

“We want the things we put in to Illumos to be usable by Oracle. This is part of why we’re not a fork,” he said.

“We’re looking at a collaborative relationship with Oracle. It should be reasonable for somebody to integrate the Illumos code back into OpenSolaris, if Oracle so chooses.”