Measuring hard drive RPM

Research and Development. This is the place to report experimental stuff related to data recovery.
fzabkar
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Measuring hard drive RPM

Postby fzabkar » Sat Apr 20, 2013 9:34 pm

Hard drives report their RPM via word 217 of their 512-byte Identify Device data block, but nowadays Western Digital obfuscates the issue with its Intellipower marketing speak. Intellipower drives have a zero in word 217. Therefore we need to detect the RPM by other means.

The best method I have been able to find is to examine the spread of data points in HD Tune's read or write benchmark graphs. AISI, the total access time is the time required to seek to the target track, plus the time required for the target sector to appear under the head. The rotational latency can vary from 0 msec up to the time required for one complete revolution. Hence the width of the access time graph must correspond to the latency of one rotation. For example, a 7200 RPM drive would have an 8 msec wide access time graph.

Here are more HD Tune results which show how RPM affects access time:

WD15EADS-00P8B0 - 5400 RPM ? (11 msec)
http://ettcweb0.aa0.netvolante.jp/log/20090830004.png

ST32000542AS Barracuda LP - 5900 RPM: (10 msec)
http://users.telenet.be/Mastakilla/H...HYS_write2.JPG

WD2001FASS-00U0B0 - 7200 RPM: (8 msec)
http://dl6.getuploader.com/g/6%7Cnew...%5B64kB%5D.png

WD5001AALS-00L3B - 7200 RPM: (8 msec)
http://bbsimg01.kakaku.com/images/bb...6/236059_m.jpg

WD1500HLFS-01G6U0 - 10K RPM: (6 msec)
http://dl7.getuploader.com/g/6%7Cnew...LFS-01G6U0.png

ST3600057SS - 15K RPM: (4 msec)
http://images.kbench.com:8080/kbench...k73831p1n6.jpg

Here are benchmark results for various makes and models:
http://hdtune.com/testresults.html

The following article shows how to measure the speed using a microphone, soundcard, and Fourier analysis software:
http://www.silentpcreview.com/article786-page2.html

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