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Free from the woes of moving parts, flash-based solid-state disks (F-SSDs) are able to operate under the harshest conditions, unlike magnetic hard disk drives. And because F-SSDs targeted for military and aerospace apps use the same fundamental flash components as the consumer realm, the price advantages can be leveraged across all markets.
The downsides associated with flash-based disks are quickly falling by the wayside. Random access speeds rival and now beat other media, retention and re-writing cycles have dramatically increased, and many systems offer a single-control erase-all function with or without power for security-sensitivity applications. Those factors have moved F-SSDs closer to the forefront as the lead option for rugged mass storage.
More Rugged than HDDs
In a rugged environment, the rotating mechanisms of a hard drive can fail, and are subject to partial and sometimes even total loss of data. Severe conditions including high shock, vibration, altitude, humidity and extreme temperature ranges increase failure rate percentages of hard disk drives, which is unacceptable for mission-critical systems. Responding to the growing demand for F-SSDs, the major vendors of F-SSD products continue to ramp the capacity, performance and security features of their products.
Exemplifying those trends is the Series 4 Data Transfer System (DTS) (Figure 1a) from L-3 Targa Systems. The unit consists of a Data Transfer Unit (DTU) and a removable Data Transfer Device (DTD), provides a compact self-contained system to store and retrieve data from 2.5-inch SATA flash disks and is designed to work in MIL-STD-810 and RTCA DO-160 environments. Capacities in this removable form factor are now available up to 256 Gbytes. The Series 4 Removable Disk Data Transfer System is used as removable storage for the Moving Map Display aboard the UK’s Tornado combat aircraft (Figure 1b).
SSD products introduced over the past 12 months span a wide range of form factors, including relatively new form factors like XMC and PCI-104. Last month Curtiss-Wright Controls Embedded Computing rolled out XMC/PMC-550, a new high-performance, rugged solid-state drive card. The XMC/PMC-550 is offered in both XMC and PMC form factor versions and is ideal for use in legacy and latest rugged deployed applications. The XMC/PMC-550’s standard Serial ATA interface enables it to be easily supported and integrated into VME VPX and CompactPCI systems.
The XMC/PMC-550 NAND flash solid-state drive provides up to 32 Gbytes of disk space in an XMC (VITA 42.3) or PMC (IEEE1386.1) form factor. It is available in configurations of 8, 16 or 32 Gbytes, and is visible to the system as two independent SATA drives. Using multi-tasking technology, the XMC/PMC-550 delivers data transfer rates of up to 30 Mbytes/s for simultaneous read to each drive. The XMC/PMC-550 also comes with RAID 0 support that stripes data across the two independent SATA drives for maximum performance.
Serial ATA Interface Dominates
Serial ATA appears to be on its way to becoming the dominate interface technology for new storage subsystem designs. SCSI and Fibre Channel in contrast seem to be waning. Apacer Technology’s newest SSD product is SATA based. The new SDM SSD (Figure 2) series is available with a 7-pin or 22-pin connector that is oriented at 90 degrees or 180 degrees and is designed for a variety of housing configurations adopted in embedded computers. Supporting SATA 1.5 Gbit/s and read and write speeds up to 35 Mbytes/s and 25 Mbytes/s respectively, the SDM offers outstanding reliability based on high-speed SLC (Single Level Cell) flash memory in capacities of 128 Mbytes to 4 Gbytes.
For strict rugged requirements, the SDM offers competitive and innovative features based on Apacer’s advanced technology. Certified for MIL-STD-810F shock-resistance and anti-vibration, the SDM is suitable for harsh operating conditions in extended temperatures of -40° to 85°C, and includes industry-leading 8-bit ECC (Error Correcting Code) for high reliability. With less than 300 defective parts per million (DPPM), the SDM has undergone on-going reliability testing (ORT) to guarantee product dependability and longevity, with a mean time between failures (MTBF) of two million hours.
Also supporting the SATA trend, Super Talent Technology has released a new line of 1.8-inch Micro-SATA SSDs aimed at rugged laptops. At merely 5 mm thick, these Micro-SATA SSDs are slimmer than most 1.8-inch hard drives, and hold up to 120 Gbytes of data. In terms of performance, power consumption and shock and vibration resistance, the MasterDrive KX is substantially better than hard drives. As a result, the MasterDrive KX makes for an excellent upgrade for military laptops that need greater reliability, or to accelerate boot-up and load times.
Built with MLC NAND flash, the MasterDrive KX is offered in 30, 60 and 120 Gbyte capacities. With 0.1 ms access time and 120 Mbyte/s and 40 Mbyte/s max sequential read and write speeds, these SSDs provide lightning fast access to files. The Micro-SATA connector in a 1.8-inch form factor makes these SSDs an ideal upgrade for UMPCs (Ultra Mobile PCs).
Size- and Weight-Constrained Apps
Small, space- and weight-constrained military applications are a natural fit for SSDs. The PCI-104 form factor–which is basically PC/104-Plus sans the ISA bus–continues to grow its territory, feeding the military’s hunger for compact, stackable systems. The LT-PCI-104-CF from Lauron Technologies is a high-performance PCI-104 32-bit, 33 MHz, 4 channel SSD RAID adapter supporting data rates of up to 120 Mbytes/s. The module adopts the PC/104 stacking architecture offering embedded designs a compact Solid-State Storage device. This single-slot adapter is available in 2 to 64 Gbyte capacities. Since the adapter houses all SSD memory, the LT-PCI-104-CF provides a single card solution for non-rotating media requirements.
The unit has an MTBF that is greater than 1,000,000 hours provided by built-in EDC/ECC and Wear Leveling algorithms. For endurance, the unit offers erase/write cycles greater than 1,000,000, with an extended version that offers 2,000,000 erase/write cycles. The benefit of the built-in flash SSD controller/bridge is that it supports Ultra DMA modes, which yield data transfers at speeds of up to 133 Mbytes/s per channel. The unit supports RAID 0, RAID 1, RAID 0+1, RAID 5 or JBOD. Striping modes transfers data to all four channels simultaneously while mirror modes transfers data on both channels.
Also targeting the size- and weight-constrained segment of the market, the Small Form Factor Special Interest Group (SFF-SIG) recently added an SSD connector spec to its list of working group projects. At ESC Boston, the SFF-SIG revealed its plans to adopt and enhance SiliconSystems’ SiliconDrive II Blade Specification for small, rugged subsystems such as mass storage and other I/O technologies under the trade name MiniBlade. SFF-SIG is expanding its portfolio of next-generation industry standards that speed and simplify the development of small embedded systems
New SSD Connector Spec
The new MiniBlade Specification, created by various suppliers for embedded applications, takes the first step toward standardizing an ultra-small, mass storage solution for the small form factor embedded system market. A plug-in peripheral card that is retained with latches in its socket withstands embedded environments better than consumer-grade dongles and thumb drives. The SiliconDrive II Blade product (Figure 4), from which the spec is derived, was jointly developed by SiliconSystems and Samtec.
This new specification now forms the cornerstone of a new SFF-SIG Working Group to define the interfaces to allow a wide array of storage, communications, GPS and other I/O products to be compatible with the MiniBlade socket. The MiniBlade Specification, to be published within the next few months, will define the mechanical form factor and interface pin definitions for MiniBlade devices.
Apacer Memory America
Curtiss-Wright Controls Embedded Computing
Aliso Viejo, CA.
San Jose, CA.