Military and ISR operations are inundated with vast amounts of data collected from an expanding network of sources, including sensor data from UAS, satellites, and remote monitoring stations. Critical information must be processed quickly and reliably, and delivered in real time to command centers and forces on the battlefield. Processing this plethora of information requires a multitude of computers, many of which are outdated or on proprietary platforms. To remain sustainable, systems used for enterprise computing, field operations, warfighting, and command and control, must be continually upgraded or replaced. Many of these systems need to be integrated, consolidated, and securely linked to multiple networks.
A New Breed of Server
A new breed of ruggedized servers designed to use COTS motherboards offer a versatile platform that can keep up with complex and ever increasing processing demands. These servers use multicore processors to pack more processing power into a smaller footprint. COTS motherboard solutions are an attractive option that gives defense customers access to the latest processor technology and industry standards. They offer benefits of high processor density, a mix of general-purpose I/O and a low entry price. These servers are upgradeable and adhere to a modular open system approach so they can be tailored with mission-specific I/O. Most importantly, they can withstand worst case scenarios in the field. To make these servers rugged, manufacturers use a wide variety of techniques at each stage of the design, manufacturing, and testing. U.S. military standards offer guidelines that help determine whether a particular product is rugged enough for a given application.
Small rugged platforms such as laptops and PDAs have become tremendously popular and are indispensable on the battlefield. Laptops are great when you need to pick up a computer and go, but if the computers are fixed-mounted, a rugged rackmount server is a better choice. In the same amount of rack space as a rugged laptop, a user can install a 1U server and have access to 2-16 CPU cores at 3.33 GHz, 48 gigabytes of RAM, 4 terabytes of storage, a PCI expansion slot, and a high-end graphics card for manipulating digital maps. A rugged server can provide 5-10 times the capability that a rugged laptop can provide, and at the same price and size profile when rack-mounted.
Rackmount servers are replacing rugged laptops in a number of mobile applications. An advantage of using a rugged server is that it can be virtualized to replace up to 16 clients. This means that one server can replace 16 laptops through the use of virtualization software. This approach is less expensive, but more importantly for mobile applications, reduces the size, weight, and complexity of equipment.
Size, weight, power, performance, cost, and cooling constraints are always important in military applications and especially so to the Navy as it upgrades its ships. For this reason, the Navy has embraced multicore servers as a means to consolidate its many applications and various independent computing platforms onto compact rackmount servers. Using highly secure software virtualization technology, it is possible to run multiple applications on the same CPU in separate partitions. This trend will undoubtedly carry over to the Army, Air Force, Marine Corps, and Coast Guard as the benefits become more apparent.
Multicore processors provide new levels of energy-efficient performance, by enabling each core to run at a lower frequency, dividing the power normally given to a single core. For rugged servers this means reduced footprint, lower power, and less thermal burden.
Commercial servers typically reside in clean, temperature controlled environments such as data centers. But what if you have to provide data center computing power on a Navy ship, an aircraft, or a UAS ground station in the middle of a desert? In military applications, shock and vibration are the norm, and extremes in temperature and weather are common.
Airborne computer applications, particularly aboard propeller-driven airplanes and rotorcraft, are characterized by sustained vibration that can shake components loose or break them. Additionally, airborne systems must not emit sparks that may ignite fuel fumes, or emit electromagnetic interference (EMI) that might disturb navigation or communications equipment. Rugged computers aboard aircraft must withstand altitudes up to 40,000 feet, and be able to survive rapid decompression.
Ground-based mobile computers are subject to vibration and shock. They must also contend with sustained temperature extremes in vehicles or shelters. Temperatures can range from -40°F in Greenland to 158°F in Saudi Arabia. Portable or partially exposed mobile computers must stand up to rain, sand, and dust. Furthermore, they are expected to operate from unregulated power with irregular waveforms, changing voltage, and frequent “brown-outs” or “drop-outs.”
Aboard ships, shock and impact resistance are critical as large vessels can be hit in combat, and smaller frigates and patrol boats can be slammed by rough seas. Electronics used on deck and exposed to the elements need protection from corrosive salt fog. Equipment EMI must be contained in order to shield the tightly packed electronics on modern vessels.
Military Standards Offer Guidelines
Ruggedized servers are used in all branches of the military and for a good reason. Rugged servers are able to withstand the intense heat and sand of the desert and can survive the bumps and jolts of an armored vehicle or naval vessel. These servers have been tested according to military standards. The fundamental guideline in rugged computing is the US Military Standard referred to as MIL-STD-810G. This series of tests was developed to determine the impact that various environmental factors have on a computer during its life, based on its anticipated usage and where it will be deployed. The drop test is probably the most challenging of these, but there are over 20 different test categories within the 810G military specification.
Furthermore, in the military world, servers must coexist with all other equipment including powerful radio, radar, and microwave transmitters as well as highly sensitive receivers. Servers must be specially configured to meet the most rigorous military needs. Specifying a computer’s EMI and its electromagnetic compatibility (EMC) is an important gauge of how well the computer will operate in “noisy” environments. MIL-STD 461 documents the EMI requirements for a wide range of applications, from trucks to ships to aircraft to fixed installations, not to mention the different requirements within an application (e.g., above deck and below deck on a Navy ship).
The MIL-STD is a guideline or tool to help customers understand the suitability of a product for a specific application. It also helps the device manufacturer tailor tests based on specific environments that a device will be used in.
Ruggedized COTS Components
Using COTS components to build rugged servers requires a mix of component and packaging modifications. Manufacturers generally start out by selecting only those COTS components that meet required criteria for the intended application. This method, called upscreening, involves profiling each component using a series of tests. Some of the tests involved are environmental stress screening (ESS) with thermal cycling, high temperature exposure, and low temperature exposure. Also, there is highly accelerated stress testing or screening (HAST) and highly accelerated life testing (HALT). Additional tests include vibration, shock, humidity, salt fog, rain, explosive atmosphere, low pressure (altitude) and fungus, among others.
Disk drives must also be selected based on application requirements. Solid state drives, based on flash technology, have proven to be rugged and perform well in extreme conditions. For this reason, they have become the leading data storage technology for almost all mission-critical military applications. With no moving parts, these devices are not hindered by seek time, latency, or other electromechanical delays found in traditional hard drives. Many systems offer a single-control erase-all function for security-sensitive applications.
Enclosures for hot climates can incorporate active-cooling solutions that range from forced air in a clean environment to sealed heat pipes or heat exchangers in sandy, dusty deserts. For applications in extremely cold environments, heaters are incorporated into the design to prevent hard-drive lubricants from thickening and liquid-crystal displays from freezing. Individual components or entire printed circuit boards can be treated with special conformal coatings to provide further protection against harsh environments. Chassis, cables, power supplies can all be shielded to meet EMI/EMC requirements.
For high availability, plug-in components are often hot-swappable allowing for replacement of failed parts without shutting down the system. Additionally, many systems can be configured with no single point of failure using redundant power supplies and failover capabilities.
COTS vendors serving the defense community are skilled at adapting commercial technology to the challenging environment presented by military applications. These include extended temperature operation, high shock and vibration, dust, salt, fog, fibers, and more. Applications, that at one time depended on full Mil-Spec components, now have a choice of COTS solutions. The defense community is increasingly receptive to COTS, and is gaining confidence that the equipment will stand up to traditionally harsh environments and operate reliably. To address the challenge of providing the most advanced technology for military applications, COTS suppliers are redesigning systems from the ground up and extending the capability of commercial components. This creates a new class of rugged servers far more durable and reliable than their civilian counterparts.