Paul Davis of Curtiss-Wright Controls Electronic Systems, considers how next generation Network Attached Storage devices are ideally suited to the defence market, to provide speed and capacity for data intensive needs
In a network centric architecture, intelligent subsystems must access mission and map information from a central file server. Because this data may come from different ground stations and different planning groups to support each function, the data required by each subsystem cannot be located on the same transportable disks.
After completion of a mission, data distribution to various ground stations also causes challenges for system designers. Different stations require different maintenance and diagnostic data collected by sensors, than mission and map information.
Many deployed military systems (fixed-wing, helicopter, UAV, shipboard, and ground vehicle) use network centric architectures for intravehicle communications. With this IP-based approach, all network clients may access a centralised storage device.
Network Attached Storage (NAS) devices first appeared in the commercial sector because:
• NSA eliminates ‘Stovepiping’ storage devices in each subsystem.
• All network clients can store data on the NAS allowing instant access to critical data by the other clients.
• Scalable, central storage allows future data growth for network clients.
• Transportable, central storage allows all network clients to have the latest data from (and back to) the ground-based, planning stations.
First generation Network Attached Storage (NAS) devices provided a single IP address on the network and only a single internal, non-removable disk stored data.
While this implementation proved useful and a good first step, the full benefit of NAS could not be realised with only one disk.
Early NAS devices provided a single Ethernet port. The first devices supported 10/100 speeds, which limited throughput.
Later, NAS devices began supporting a single gigabit Ethernet (1.25Mb/s) speed, which helped to expand throughput, but limited access without a network switch present.
These early NAS devices often relied on PCMCIA card technology. While widely accepted at the time, this technology has reached end of life. PCMCIA has slower access speed, less storage capacity and little growth potential compared to modern solid state drives (SSD).
Second generation NAS devices
Using second-generation NAS devices (shown in Figure 1), two removable flash-based drives appear as one network drive to the network client. Each of the removable drives includes four SATA SSDs. With two drives, this storage device provides scalable, removable storage and thus allows data growth. But the singular, common network drive approach limits the distribution of data after the mission.
The example device includes four gigabit Ethernet ports. This generational enhancement allows four different subsystems (mission computer, sensor management computer, display, communications) to directly access the central NAS storage. With four network switches attached to each of the four 1GbE ports, dozens of subsystems can access the storage.
These SSD based devices provide a speed and capacity advantage over PCMCIA-based earlier NAS devices.
The storage capacity of these NAS devices has grown from hundreds of gigabytes to terabytes as memory technology improves. With continued advances in flash memory technology, such storage increases are expected to continue for many years to come.
Data for an aircraft or vehicle mission is often generated by multiple sources on the ground. The basic groups of data include mission, map, and maintenance:
• Mission data comes from the mission planning system. The mission data provides instructions to the mission computer and possibly other subsystems (or backup system).
• Multiple ground station systems generate map data. Interactive displays and other systems use the map data.
• Maintenance and diagnostic data is generated on the aircraft or vehicle by the various subsystems and attached sensors.
Aircraft have many sensors capturing information important to the maintenance crews. These sensors report on temperature, shock, vibration, and other critical factors. Such data tells the story of the stresses on the aircraft or vehicles and provides information for planning scheduled maintenance.
Data from each of these drives must go back to specific de-brief stations. Next generation NAS devices enable NAS systems to allow direct network access to each disk.
To the attached network clients, next generation NAS devices provide access to each SSD drive and each is individually addressable. The subsystem clients can map each of the drives as an individual drive in its drive tables.
This flexibility is the next step in the advancement and usability of Network Attached Storage devices. Now the pilot can collect the mission, map, and maintenance disks from three different planning systems and install the drives into a single data transport chassis.
The mission computer can retrieve plan data from the mission disk; the display system can access terrain information from the map disk and sensors and other subsystems can save maintenance and diagnostics data on the maintenance disk.
Today’s system designers have begun to take advantage of network centric architectures to increase interconnectivity, flexibility, and reduce risk & SWaP. With each block and program phase, more network devices are integrated into a vehicle’s network.
Data storage is essential to mission planning and success. Mission, maps, and maintenance data continue to demand higher throughput and larger storage capacity as the quantity of data generated increases. This increasing trend is not likely to stop.
NAS plays a critical role in these network centric systems. Third generation NAS devices provide multiple, high-speed 1GbE ports, and individually addressable disks.
Future networks will leverage these advancements in NAS storage devices.
