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Why does mechanical failure causes HDD being undetectable by bios or OS ?

Discussion in 'PC Hardware' started by andy, Sep 3, 2004.

  1. andy

    andy Guest

    Could someone please explain why in the case of *mechanical* failure HD
    becomes sometimes undetected by BIOS and/or the operating system (e.g. win xp
    or linux)?
    If it was an electronic failure then such behaviour would be obious, but why
    the same happens with some mechanical failures? When electronics is working in
    my opinion it still should be detected by bios and/or the system (win xp or
    linux), but often it is not.
    I could recover about 80% of the data from my HDD (which apparently has a
    mechanical failure - plates spin up and down, heads create bad noises) if only
    the disk could be seen by the system all the time. But often during copying of
    the data heads hit with a loud sound so badly that sometimes even the plates
    stop rotating, and the disk then dissapears from the system. It is then very
    difficult to make it detectable by the system again, sometimes the sytem can
    detect it but only after several minutes of copying it freezes and then
    dissapears again.
    Recently, I was unlucky, and even after several dozens of retries it's still
    undetectable by the system.

    Could you please advice what to do to make the disk detectable by the system
    all the time?
    What causes that it is not detectable although the failure is in mechanics not

    BTW, if someone has the same disk model (Quantum Fireball ST64A011), please
    let me know.

    andy, Sep 3, 2004
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  2. andy

    CWatters Guest

    This sounds like a classic head crash. The heads are physically rubbing on
    the platters causing damage to both. Onee that happens it's only a matter of
    time before the drive is completly dead.
    CWatters, Sep 3, 2004
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  3. andy

    andy Guest

    It still doesn't explain why head crashes causes disk to be undetectable at
    times (well, most of the time in this case).
    I opened the disk (I don't care about the dust, since it's dead anyway), and
    the surface of the first plate is in perfect condition, I can't see surfaces
    of other plates, though.

    BTW freezing didn't help to detect it.

    andy, Sep 3, 2004
  4. If the disk is not spinning at the required speed it is not READY, and
    cannot be read. The system cannot read devices which do not decalare
    themselves as READY!
    Michael Hawes, Sep 3, 2004
  5. andy

    Ron Reaugh Guest

    Ron Reaugh, Sep 4, 2004
  6. andy

    CWatters Guest

    You can't always see the damage with the human eye until it's really very
    CWatters, Sep 4, 2004
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