The Navy’s newest warship is powered by Linux

When the USS Zumwalt (DDG 1000) puts to sea later this year, it will be different from any other ship in the Navy's fleet in many ways. The $3.5 billon ship is designed for stealth, survivability, and firepower, and it's packed with advanced technology. And at the heart of its operations is a virtual data center powered by off-the-shelf server hardware, various flavors of Linux, and over 6 million lines of software code.

On October 10, I flew up to Rhode Island to visit Raytheon's Seapower Capability Center in Portsmouth, where engineers assembled and pre-tested the systems at the heart of the Zumwalt and are preparing to do the same for the next ship in line, the USS Michael Monsoor—already well into construction. There, Raytheon's DDG-1000 team gave me a tour of the centerpiece of the ship's systems—a mockup of the Zumwalt's operations center, where the ship's commanding officer and crew will control the ship's sensors, missile launchers, guns, and other systems.

Over 20 years ago, I learned how to be a ship watch stander a few miles from the Raytheon facility at the Navy's Surface Warfare Officer School. But the operations center of the Zumwalt will have more in common with the fictional starship USS Enterprise's bridge than it does with the combat information centers of the ships I went to sea on. Every console on the Zumwalt will be equipped with touch screens and software capable of taking on the needs of any operator on duty, and big screens on the forward bulkhead will display tactical plots of sea, air, and land.

Perhaps it's appropriate that the first commanding officer of the Zumwalt will be Captain James Kirk (yes, that's actually his name). But considering how heavily the ship leans on its computer networks, maybe they should look for a chief engineer named Vint Cerf.

Off the shelf and on the ship

In the past, you couldn't just put off-the-shelf computer systems aboard a ship for mission critical tasks—when I was aboard the USS Iowa, we had to shut down non-tactical systems before the guns were fired because the shock and vibration would crash systems hard. So typically, individual computer systems are ruggedized. But that adds heavily to the cost of the systems and makes it more difficult to maintain them.

The design of the Zumwalt solves that problem by using off-the-shelf hardware—mostly IBM blade servers running Red Hat Linux—and putting it in a ruggedized server room. Those ruggedized server rooms are called Electronic Modular Enclosures (EMEs), sixteen self-contained, mini data centers built by Raytheon.

Measuring 35 feet long, 8 feet high, and 12 feet wide, the 16 EMEs have more than 235 equipment cabinets (racks) in total. The EMEs were all configured and pre-tested before being shipped to Bath, Maine, to be installed aboard the Zumwalt. The EME approach lowered overall cost of the hardware itself, and allows Raytheon to pre-integrate systems before they're installed. "It costs a lot to do the work in the shipyard," said Raytheon's DDG-1000 deputy program manager Tom Moore, "and we get limited time of access."

Each EME has its own shock and vibration damping, power protection, water cooling systems, and electromagnetic shielding to prevent interference from the ship's radar and other big radio frequency emitters.

The EMEs tap into the Total Ship Computing Environment, the Zumwalt's shipboard Internet. Running multiple partitioned networks over a mix of fiber and copper, TSCE's redundantly switched network system connects all of the ship's systems—internal and external communications, weapons, engineering, sensors, etc.—over Internet protocols, including TCP and UDP. Almost all of the ship's internal communications are based on Voice Over IP (with the exception of a few old-school, sound-powered phones for emergency use).

There's also some wireless networking capability aboard the Zumwalt, but Raytheon officials giving me the tour were not at liberty to discuss just what sort of wireless this is. Still, that capability is supposed to allow for roving crew members to connect to data from the network while performing maintenance and other tasks.

Systems that weren't built to be wired into an IP network—other "programs of record" within the ship, which are installed across multiple classes of Navy ships—are wired in using adaptors based on single-board computers and the Lynx OS real-time Linux operating system. Called Distributed Adaptation Processors, or DAPs, these systems connect things like the ship's engineering systems, fire suppression systems, missile launchers, and radio and satellite communications gear into the network so they can be controlled by networked clients.

It looks like you want to launch a missile

Some of those networked clients were what I was looking at in the mocked-up Zumwalt operations center. The operations center isn't just where screens are watched and commands are shouted—the whole ship can be practically run from the space, from guns and missiles to engines. There's no "radio room" on the Zumwalt; all the communications are managed from the operations center. The ship's guns are fully automated and operated by an operations center watch stander instead of a gunner's mate in the mount. Theoretically, the ship could even be steered from the ops center—the ship is piloted by computer, not a helmsman. And all of these tasks are performed from the same type of console.

Called the Common Display System, or CDS (pronounced as "keds" by those who work with it), the three-screen workstations in the operations center are powered by a collection of quad-processor Intel motherboards in an armored case, which gives new meaning to the nautical phrase "toe buster." Even the commanding officer's and executive officer's chairs on the bridge have CDS workstations built-in.

Each CDS system can run multiple Linux virtual machines atop LynuxWorx's LynxSecure, a separation kernel tthat has been implemented in CDS as a hypervisor. This allows the workstation to connect to various networks partitioned by security level and purpose. "Every watch stander station runs out of the same box," Raytheon's DDG-1000 developer lead Robert Froncillo told me. "So they can sit at any CDS and bring up their station."

This may not seem like a big deal to most people. But on past ships, workstations tended to be purpose-built for a specific weapons system or sensor. That meant every system had a different configuration and interface, and you couldn't have a watch stander handle multiple tasks without having to switch seats. The CDS workstation uses common USB interfaces for its peripheral devices (such as trackballs and specialized button panels) and is equipped with touchscreens, as well, so that watch standers have a choice between "classic" and touch interfaces.

That doesn't mean there's necessarily a "Clippy" to help new operators master their systems. The Raytheon team has had sailors in to perform usability assessments from before code was even written, showing them screen shots of interfaces to get feedback from users. "We had a chief that said, 'We don't want any 'wizards,'" said Froncillo.

Putting all of the pieces together is a collection of middleware running on those IBM blade servers. Many of the shipboard systems use a commercial publish/subscribe middleware platform to send updates to operator consoles. But for other systems that need to be more tightly coupled (like, for example, missile launch commands), the Navy has specified the use of the Common Object Request Broker Architecture (CORBA)—the military's favorite mission-critical middleware model. (The software for the Joint Tactical Radio System's software-defined radios was also developed using CORBA.)

The next release

The Zumwalt may not have sailed yet, but its software has already shipped six times. When Release 5 was completed, Raytheon brought in more sailors to test the system, tethering it to the company's Total Ship System Simulator to run through a number of combat scenarios. "We did antisubmarine warfare, air, and land attack missions," Froncillo said. The lessons learned were incorporated into release 6, and 7 will be installed on the ship before the ship's "shakedown" cruise. Another upgrade will be installed post-delivery, and continual improvements will be made as the software is deployed to the other two ships in the class.

But the life of the technology being deployed on the Zumwalt won't end there. CDS will be used as part of the Navy's Aegis Modernization Program to upgrade the systems of the fleet's guided missile cruisers and destroyers. "And there are a lot of things we're developing that will be reused," Moore said.

Considering how much has been spent over the past decade trying to get the Zumwalt built, and the other technologies that were developed in the process, one can hope that more than just the software gets some reuse.