Advantech and HDD 411: The Five Main Categories

I have a growing stash of reference materials that I keep at hand, and I find use for at least one item in this collection every workday. Most are in PDF format, and, to make sure that they are indeed “at hand,” I keep them in cloud-based storage that syncs automatically to the drives on my various devices, ensuring all of these documents are accessible wherever, whenever, and via whatever device is available – even when I don’t have an Internet connection. For example, this file contains the latest version of the Associated Press Stylebook to remind me that I should capitalize “Internet” here and that “web site” is properly written as two words, as well as other such rules of high-tech grammar.

I added another PDF to my reference file today – one that I’m sure to use regularly, given the ubiquity of the devices it covers – Advantech’s HDD Performance Whitepaper. At 19 pages, the report is brief enough that I’ll actually use it, detailed enough to contain the critical data I need, and recent enough (September 9, 2013) to ensure that its data covers the latest hardware configurations.

All data presented in the report was verified by Advantech through actual, independent tests conducted from 2009-2013 and analyzes all potential configuration variables, including the various available SATA specifications, spindle speeds, platter densities, capacities, and cache types.

The report separates its data out into five main categories:

  1. SATA Specifications: The Serial Advanced Technology Attachment, or SATA, serial interface presents best/worst burst speeds of 138/107 MB/s in SATA 1, 268/163 MB/s in SATA 2 and 453/270 MB/s in SATA 3.
  2. Spindle Speed: Spindle speed obviously effects hard-drive speed in terms of seek time and transfer rates, but to what extent? When spindle RPM was compared to random access time in milliseconds, the results were 4200/17, 5400/14.8, 5900/14.8, 7200/10.6 and 10000/6.3 (RPM/random-access-time/ms). The impact of spindle speed on seek time is dramatic, although not quite linear. When spindle RPM was compared to random read in MB/s, the results were 4200/42, 5400, 105, 5900/167, 7200/197 and 10000/174. Here, faster spindle speed achieved a point of diminishing return at 7200 RPM.
  3. Storage Per Disk: Intuition would predict that the greater the density of data storage a disk platter, the faster it can be accessed and read, but the relationship is not that simple, and it’s nice to know the actual numbers. In terms of density-per-disk/average-read in MB/s/random-access-time in milliseconds, the data results are summarized as 80G/28/19, 100G/42/17, 160G/94/12.5, 250G/116/12, 320G/107/14.2, 500G/125/11.5 and 1000G/197/6.7. Again, not quite linear.
  4. Cache Size: Of course, cache size impacts hard-drive efficiency, as well. In terms of cache/average-read-rate in MB/s/random-access-time in milliseconds, the results are 8M/114/15.1, 16M/113/14.2, 32M/118/12.3 and 64M/125/11.5.
  5. Performance by Application: HDD performance also varies by application of which the three main categories are Industrial PC, Video Surveillance and Enterprise. For example, many industrial-PC applications areAIMB-554VG-00A1E-2T powered for just 8 hours per day and 5 days per week, while most video-surveillance and enterprise applications are subjected to 24/7 duty, with endurance being a more significant factor in the architecture of HDDs delivered for those later two categories. Enterprise-ready HDDs are typically delivered with spindle speeds as high as 15000 RPM, while HDDs for industrial-PC and video-surveillance usually top out at 7200 RPM. Considering all relevant factors, the average-read-rates (MB/s) and random-access-times (ms) for HDDs destined for industrial-PC, video-surveillance and enterprise applications were, respectively, 197/10.6, 192/10.7 and 177/6.3.

More data, greater detail and graphs, to boot, are available in the original whitepaper, but you’ll have to register with the Advantech web site to access that PDF, and, given the quality of information available there, that’s clearly worth doing!