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Harddisk motion detection?

Discussion in 'Electronic Repair' started by Bart Bervoets, Oct 3, 2006.

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  1. Is it possible that inside certain harddisks motion detectors are placed?
    I have a harddsk which works fine but as soon you move the drive (powered on
    and connected to pc)
    the head sounds as it wants to go in park, if i leave the drive alone it
    just works fine.
    IDE and power cable are ok.
    Not relevant for a repair but plain curiosity, i would expect it on a laptop
    disk but not a desktop.

    Bart Bervoets
  2. Meat Plow

    Meat Plow Guest

    I can safely say that no modern drive has any such thing.
  3. Some laptops and external harddrives for laptops do have shock detectors but
    I don't know if they are inside the drives.

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  4. You should never move a running drive. It could crash.


    50% of all statistics are wrong. The rest don't matter.

    Clyde Crashcup
  5. Meat Plow

    Meat Plow Guest

    LOL that made me laugh.
  6. Meat Plow spake thus:
    Yeah, I guess all those people using laptops must just *imagine* they're
    moving their computer while it's on.
  7. James Sweet

    James Sweet Guest

    Most microdrives have this feature, but these are the tiny drives the
    size of CF cards used in many portable music players. Just moving it
    should not trigger it though, it takes a fair bit of shock.
  8. Hi!
    Anything is always possible. But I doubt that there is any such thing in a
    desktop hard drive. Laptop drives may have such circuitry in place.

    Based on some drives that I've worked with over time, I'd say what you're
    seeing is likely a result of the spindle motor somehow changing speed
    slightly as you move it. The drive's controlling electronics can monitor the
    RPM of this motor and may shut the drive down if enough of a change is
    detected. The motor may be getting ready to fail or it may have worn
    bearings that allow a significant RPM change when you move it.

    You can get most desktop drives to reinitialize themselves with a mild tap.
    I don't suggest trying that on a drive you depend upon. And while it
    generally does no harm to move a running hard drive, you should be careful
    not to drop, jar, shake or abuse it while it is running. If any one of those
    things were to happen while the drive was running, a head crash or other
    drive failure is possible.

  9. One notorious 10 Mb hard drive Radio Shack sold would only start after a
    weekend if you first dropped it about a foot onto a desk!
  10. Morse

    Morse Guest

    I've seen many, many drives like that- it's called 'stiction'. The heads and
    platters are so perfectly formed and smooth that they can bond together
    preventing the drive motor spinning up the platters. Usually the motor can
    be heard pulsing and giving up after a few tries. The best way to release
    the heads from the platters is IME to hold the drive and quickly flick it in
    a rotational plane to spin the internal platters breaking the bond. Freezing
    the drive overnight can also do the trick, but the drive must be put in a
    completely sealed bag beforehand. Warming with a hairdryer can also help.
    Thumping the drive onto a hard surface should be a last resort.

    Stiction is not usually an issue on modern drives, but it was common on the
    old MFM/RLL/ESDI style drives.

  11. Morse

    Morse Guest


  12. JW

    JW Guest

    You're going to crash your heads, if you already haven't. A hard drive
    should not be moved when running.
    It's probably getting an error and recalibrating.

  13. Yep, many do, to prevent head crashes when the drive gets jostled. Get
    the drive model number and look up the manual on the Internet (a set
    of tubes). It's there plain as day.

    As a side effect, it turns out to be quite possible to set up an ad-hoc
    earthquake monitoring network, just with a little added software!
    Very clever!
  14. Ancient_Hacker spake thus:
    Sorry, you lost me there. "Set of tubes"; what is that?
  15. One of our more cretinous representatives stood up and blathered in
    Congress about how the Internet is getting clogged up as one of his
    staffers sent an "internet" to him and it took four days to arrive.
    You see the Internet "it's like a set of tubes".
  16. Ted Stevens of Alaska and the bridge to nowhere and secret spending.
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