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What happens with HDD if power is lost?

Discussion in 'Storage' started by Swamp Monster, Jan 22, 2011.

  1. Swamp Monster

    Swamp Monster

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    Do reading heads fall on platters when power is suddenly lost? What happens then? What if drive has NoTouchâ„¢ ramp load technology or similar, and what difference does it make?
     
  2. scaminatrix

    scaminatrix

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    My rig's failed/powered down/reset while in use hundreds of times, sometimes while crunching, sometimes while WinRAR's extracting etc. I would imagine this is the same thing, so I would guess, nothing would happen 999 times out of 1000.
    Maybe you'd lose/corrupt data but not much worse.

    Now watch me get bashed by a pro :laugh:
     
  3. freaksavior

    freaksavior To infinity ... and beyond!

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    Usually nothing but it's certainly not good for it.

    You want the drive to be able to stop reading/writing data before the motor shuts off but if you kill the power for example, it won't damage your drive, it will simply stop, I think that's the part of the reason you have a buffer.
     
  4. Solaris17

    Solaris17 Creator Solaris Utility DVD

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    I dont think they touch. Im almost certain HDD's are designed to stop at a certain point when the head drops. This prevents damage to the head and the platter. during power failure etc.
     
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  5. meran

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    hmmm i havent heard any one here says that he lost his hdd from power lost but data corruptions happens allot from that sometimes windows doesn't boot but it doesnt die unless u knock ur case out
     
  6. Swamp Monster

    Swamp Monster

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    For some time now I think that only bad thing that can happen when power is suddenly lost, is that HDD head can fall on spinning platter, and that shortens it's life. It is because WD says, that their new technology prevents head from touching the platter. I assume that if older models has not similar technology, then head can touch the platter. Data corruption doesn't bother me, only HDD health.

    *edit* I found interesting material that confirms my suspicion:
    http://www.google.lv/url?sa=t&sourc...682aCA&usg=AFQjCNHfGF-xEWDEHEa1NPcU4UYhvqSdyw

    To me it sounds ankward that head is safely parked in area, that is bumpy/rough, but I guess it needs to be that way.
     
    Last edited: Jan 22, 2011
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  7. meran

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    one time i bought a pc for someone i bought a hitachi 160gb and he drop it 3 feet from the ground i didn't work at all the hard drive have to power down it self in shut downs and windows just stop access it and power supply turn off nothing with heads or stuff
     
  8. sneekypeet

    sneekypeet Unpaid Babysitter Staff Member

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    Only issue I have ever had from a improper shutdown was that when i rebooted, windows wanted to repair the drive or do a disc check. Either way, once they were done working their magic, all was good to go on the next boot. I wouldn't be too worried about it.
     
  9. Swamp Monster

    Swamp Monster

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    The bad thing is - that heads really CAN touch platters, and damage them or head itself.
    From that Pdf I understand that all these safety techniques work by informing controller, thus only if power is avaliable.
     
  10. freaksavior

    freaksavior To infinity ... and beyond!

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    The heads float, it's not like a vinyl.

    Think of it like this,

    the heads are giving the disk a blow job, they can't be rough with it or they will damage the goods.
    So power failure doesn't = bad blow job
    power failure = finished blow job, that's all
     
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  11. Swamp Monster

    Swamp Monster

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    But when power suddenly disappears they don't float anymore - they land on goods and when drive spins up next time, goods get damaged;)
     
  12. Frick

    Frick Fishfaced Nincompoop

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    I don't think they ever touch the plates. If you ever tear a harddrive apart you'll notice the buggers is hard to budge.
     
  13. Swamp Monster

    Swamp Monster

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    I have included Pdf file in my second post, did you read it? Maybe you have good, new HDD model, and something has changed?
     
  14. Frick

    Frick Fishfaced Nincompoop

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    I read it now real quick, and the second paragraph says:

    "All drive manufacturers have an auto park feature that safely parks the heads over the landing area when drive is spinning down".

    It seems like they can land on the surface, but the manufacturers have taken steps to avoid it, that HP thing just one of them. Interesting.

    EDIT: Maybe this is done magnetic somehow? There are some strong ass magnets in harddrives.
     
  15. scaminatrix

    scaminatrix

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    That's the best hard drive analogy I've ever heard!
     
  16. Frick

    Frick Fishfaced Nincompoop

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    It actually says how it works in the PDF, look at the picture provided.
     

    Attached Files:

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  17. meran

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    LOL:laugh::laugh::laugh::roll::roll: thats the point
     
  18. theonedub

    theonedub habe fidem

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    Deconstructed: Hard Disk Drive
    http://www.youtube.com/watch?v=-YHhzQJWOtE

    Heads never touch.
     
    Crunching for Team TPU
  19. Frick

    Frick Fishfaced Nincompoop

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    So it's true then? Then why is it mentioned in that PDF document? Granted it is from 1999, but still.
     
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  20. Perseid New Member

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    Many years ago, hard drives heads used to stop wherever they were when the drive lost power. If you then moved the computer, the motion could cause the head to bump the drive. At best you scratch the platter and lose some data. At worst you snap the head right off. There used to be programs for DOS that would manually park your HDD before you turned the computer off in case you were going to put the computer in a vehicle or something.

    Heads now snap back when they lose power and this can't happen anymore.
     
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  21. theonedub

    theonedub habe fidem

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    I imagine the landing zone is away from the platters that store the data. So who cares what it does there, its not going to effect the data on the drive.
     
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  22. Swamp Monster

    Swamp Monster

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    My point is that if power is lost, then heads never make it to the landing zone. I would be happy to know something based on facts, that it has now changed. If parking is done really fast by magnets, then it's cool, but I need a proper confirmation to be really sure.
     
  23. ivicagmc

    ivicagmc

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    I heard that the greatest damage happens when you start in an early, cold morning. Could be that distance between head and the platter is so small that it actually, because of shrinking, touches the platter?
     
  24. theonedub

    theonedub habe fidem

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    I really hate to cite Wikipedia, but:


    Modern HDDs prevent power interruptions or other malfunctions from landing its heads in the data zone by parking the heads either in a landing zone or by unloading (i.e., load/unload) the heads. Some early PC HDDs did not park the heads automatically and they would land on data. In some other early units the user manually parked the heads by running a program to park the HDD's heads.

    A landing zone is an area of the platter usually near its inner diameter (ID), where no data are stored. This area is called the Contact Start/Stop (CSS) zone. Disks are designed such that either a spring or, more recently, rotational inertia in the platters is used to park the heads in the case of unexpected power loss. In this case, the spindle motor temporarily acts as a generator, providing power to the actuator.

    Spring tension from the head mounting constantly pushes the heads towards the platter. While the disk is spinning, the heads are supported by an air bearing and experience no physical contact or wear.

    Basically what Perseid had explained.
     
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  25. meran

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    OMG and why there is engineers in this planet what they do the take all considerations they took power cuts now dropping what else power surge protection?:laugh:
     

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