| The Evolution of Storage |
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| Mar 01 2008 | |
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advertisement: In terms of rugged operation, solidstate drives are far and away the more capable choice. Nothing kills rotating drives like excessive shock, vibration and temperature conditions. The cost of a ruggedized rotating system goes well beyond the raw cost per gigabyte; in fact, the long term cost to mitigate the effects of harsh conditions is estimated to be anywhere from 5X to 50X the original cost of the drives, depending on the specific requirements. Harsh industrial and military environments share similarities, both in terms of rugged requirements and cost sensitivity, so it’s important to look at the big picture. Ruggedization and maintenance costs over and above the initial lower cost of rotating drives can be placed into two categories, and when combined, can easily surpass any savings recognized at the onset of a project or program. It may well be that solid-state flash drives are now less expensive over the long run than rotating drives (Table 2). In addition to durability, solid-state flash drives bring to the table a host of security features including secure erase (sanitization) and write protect. Data erasure in rotating hard drives is software driven and can take roughly one hour to erase 20GB of data, with no guarantees that residual data images don’t still remain for the taking. By contrast, it takes approximately 20 seconds to erase a 16GB solid-state drive, leaving little or no residual data. In both cases, the question of whether or not this sanitization meets mil requirements is a topic of debate and a separate discussion. The PMC SecureStor from ACT/Technico uses an FPGA implementation for hardware enabled secure erase and write protect on a Compact Flash drive. Hardware activation allows the erasure function to continue as long as power is applied, and unlike software driven erasure, is not dependent on the software running in the processor. Read and write access times are comparable between solid state and rotating drives, and flash capacities in 2.5" drives are set to break the 128GB threshold soon. For most industrial applications, current capacities and bandwidth capabilities in both drive types is sufficient. Serial ATA Hitachi, Fujitsu and Seagate, the three pre-eminent rotating hard drive manufacturers, have either EOL’d (end of life) their 2.5" 7200 RPM enhanced duty IDE/ATA parallel ATA (PATA) drives, or will soon in favor of the same breed of drives in Serial ATA (SATA) format. This follows the industry trend away from parallel interfaces driven primarily by the PC market. Only Seagate plans to manufacture 5400 RPM PATA drives past December with two rugged models targeted primarily for the embedded market. All three companies continue to manufacture 4200 RPM PATA drives. |
