Defragment your disk before data falls off!



  • Hi,

    this is my first post, and it's only a small one, but I can't stop laughing about what the Admin in my company just told me:

     
    He actually met a guy (a self-proclaimed computer expert) who insisted that disk fragmentation was the result of centrifugal force. The spinning disk - he said - was moving the data from the center to the outer regions and the defragmenter should be used regularly to put it back in place...


    Since hearing this I've been very worried about my files...



  • [quote user="tdittmar"]

    Hi,

    this is my first post, and it's only a small one, but I can't stop laughing about what the Admin in my company just told me:


    He actually met a guy (a self-proclaimed computer expert) who insisted that disk fragmentation was the result of centrifugal force. The spinning disk - he said - was moving the data from the center to the outer regions and the defragmenter should be used regularly to put it back in place...


    Since hearing this I've been very worried about my files...

    [/quote]

    Thank goodness someone told me, I wouldn't want little bits of data filling the bottom of my hard drive case, they may end up bending the platters if too much falls off!



  • Remember folks that centrifugal force is a virtual 'reactionary' force to the true centripetal force as defined by one Isaac Newton.



  • But Galileo killed the myth that things fall off the sides a disk...



  • Well, no. He didn't say "things can't fall off a disk" - he said "your disk isn't really a disk". Which directly leads to the question: Could we get rid of defragmenters if we used "Hardspheres" instead of "Harddisks"?



  • [quote user="tdittmar"]Well, no. He didn't say "things can't fall off a disk" - he said "your disk isn't really a disk". Which directly leads to the question: Could we get rid of defragmenters if we used "Hardspheres" instead of "Harddisks"?
    [/quote]

     
    I think it actually leads to the question, are hard disks really disks at all?

     



  • Is there a special name for a very flat cylinder (a real-life "disc") that is pinched in the middle?



  • [quote user="dhromed"]Is there a special name for a very flat cylinder (a real-life "disc") that is pinched in the middle?
    [/quote]

     A cone?



  • [quote user="tdittmar"] "your disk isn't really a disk".
    [/quote]

    Hey, speak for yourself, buddy! 

     



  • [quote user="pinkduck"]Remember folks that centrifugal force is a
    virtual 'reactionary' force to the true centripetal force as defined by
    one Isaac Newton.[/quote]

    There's no such thing as centripetal force.

     



  • [quote user="Cratig"]

    Thank goodness someone told me, I wouldn't want little bits of data filling the bottom of my hard drive case, they may end up bending the platters if too much falls off!

    [/quote]

    This actually happened to me once. What a mess!

     



  • [quote user="tdittmar"]

    Hi,

    this is my first post, and it's only a small one, but I can't stop laughing about what the Admin in my company just told me:

     
    He actually met a guy (a self-proclaimed computer expert) who insisted that disk fragmentation was the result of centrifugal force. The spinning disk - he said - was moving the data from the center to the outer regions and the defragmenter should be used regularly to put it back in place...


    Since hearing this I've been very worried about my files...

    [/quote]

    The carpenter and his sawhorse is back. Yes, he met your sysadmin. Unless someone didn't become a self-proclaimed computer expert by reading TDWTF.



  • Similarly, you need to be careful about carrying a USB flash device in
    your pocket, as it is possible for the data to be knocked loose as you
    walk around.



  • [quote user="Thanny"]

    There's no such thing as centripetal force.

    [/quote]

    I think you mean there's no such thing as centrifrugal force.  It's officially a pseudo-force.  The centripetal force is a real force (i.e. it is not just a product of the rotating coordinate system, as the centrifrugal pseudo-force is).

    But I don't know why people get so precious about forces and pseudo-forces.  There's not really any such thing as a "force" either.  It's just an approximation to some highly complex integrals involving electromagnetic attraction and the Pauli exclusion principle.



  • [quote user="tdittmar"]

    Hi,

    this is my first post, and it's only a small one, but I can't stop laughing about what the Admin in my company just told me:

     
    He actually met a guy (a self-proclaimed computer expert) who insisted that disk fragmentation was the result of centrifugal force. The spinning disk - he said - was moving the data from the center to the outer regions and the defragmenter should be used regularly to put it back in place...

    [/quote]

    Next time, tell your expert that he's absolutely right, and that defragging works by spinning the disk in the opposite direction.



  • This makes me think of something similar that I once heard.

    A problem occurs in one of IBM's supercomputers (the 360/190, maybe?  or the 370/195?  Early 1970's).  The traces on the circuit boards are extremely small and thin, and over time the electrons going "in one direction" (as I was told) put pressure on the atoms until the traces stretch and break and the boards stop working.

    Sounds bogus to me, because the traces within an integrated circuit are so much tinier and they don't stretch and break, as far as I know.

     



  • [quote user="newfweiler"] This makes me think of something similar that I once heard.

    A problem occurs in one of IBM's supercomputers (the 360/190, maybe?  or the 370/195?  Early 1970's).  The traces on the circuit boards are extremely small and thin, and over time the electrons going "in one direction" (as I was told) put pressure on the atoms until the traces stretch and break and the boards stop working.

    Sounds bogus to me, because the traces within an integrated circuit are so much tinier and they don't stretch and break, as far as I know.[/quote]

     Actually, the second version of this (for IC's) is a real problem - it's called electromigration:

    To get significant eletromigration in a macroscopic conductor like a circuit-board trace, you'd have to pass a lot of current through it for a very long time, so I'm pretty sure that's never happened. It's only the teeny-tiny size of the wires in an IC that makes them susceptible to the effect.



  • This explains things.  The other day my hard drive was making a funny noise, and then something flew out and smacked me in the face.  Further checking showed that my 2002 tax return was missing.  This was the heaviest file on my system, and I can only conclude it must reached the edge of the disk and achieved terminal velocity.



  • This is a very old joke that gets passed around computer labs. Occasionally, some idiot believes it.

    Unfortunately, it's impossible to tell whether the guy your admin met was an idiot, or just thought your admin was an idiot.



  • [quote user="EddiePedant"][quote user="Thanny"]

    There's no such thing as centripetal force.

    [/quote]

    I think you mean there's no such thing as centrifrugal force.  It's officially a pseudo-force.  The centripetal force is a real force (i.e. it is not just a product of the rotating coordinate system, as the centrifrugal pseudo-force is).[/quote]

    Sigh... Centrifugal force is just as real as centripetal force is. It all depends on your frame of reference (or if you prefer, "coordinate system"). A rotating frame of reference is every bit as valid as an inertial one, if you're inside it.

    [quote user="EddiePedant"]But I don't know why people get so precious about forces and pseudo-forces.  There's not really any such thing as a "force" either.  It's just an approximation to some highly complex integrals involving electromagnetic attraction and the Pauli exclusion principle.[/quote]

    True enough, but hey, if you're going to have forces, at least they should be consistant. In any consistant definition of force, both centripetal and centrifugal forces are equally "real". Just not in the same frames. :)



  • If the bits fall off the edgeof the disk, should one put a container under the disk to catch them. If so can we call it the bit bucket? Will we have to empty said bit bucket?



  • [quote user="Otto"]

    Sigh... Centrifugal force is just as real as centripetal force is. It all depends on your frame of reference (or if you prefer, "coordinate system"). A rotating frame of reference is every bit as valid as an inertial one, if you're inside it.

    [/quote]

    Newton's Laws are only valid in an inertial frame.  A rotating frame of reference is therefore not "every bit as valid" as an inertial one.

    A good example is a frame which is falling to Earth with acceleration 2g.  From this frame it appears that an "anti-gravity" force exists which causes anything not tied down to move upwards with acceleration g.  Is that force "real"?  Do we really have to accept "anti-gravity" as fact in order to analyze what happens?  No.  We simply accept it as a pseudo-force - an artefact of using a non-inertial frame.

    But, if we wanted to calculate in this 2g frame a lot, we might just use this "anti-gravity" pseudo-force to make our calculations a bit easier.  Would "anti-gravity" be any more real then?

    It's the same for rotating frames and centrifugal force.

    [quote user="EddiePedant"]

    But I don't know why people get so precious about forces and pseudo-forces.

    [/quote]

    Actually I take that back.



  • [quote user="darin"]This explains things.  The other day my hard drive was making a funny noise, and then something flew out and smacked me in the face.  Further checking showed that my 2002 tax return was missing.  This was the heaviest file on my system, and I can only conclude it must reached the edge of the disk and achieved terminal velocity.
    [/quote]

     

    Don't you mean Escape Velocity?

     Anyway, I was thinking this would explain what happened to my 80 gig drive FDisk'd with Windows 98...

     which had a 64 gig limit... the 65'th gig got mapped to the first gig... goodbye partition table, root directory...



  • [quote user="tdittmar"]

    He actually met a guy (a self-proclaimed computer expert) who insisted that disk fragmentation was the result of centrifugal force. The spinning disk - he said - was moving the data from the center to the outer regions and the defragmenter should be used regularly to put it back in place...

    [/quote]

    I'm guessing that this "expert" lives in a rural area. been there...



  • [quote user="bgodot"]

    [quote user="darin"]This explains things.  The other day my hard drive was making a funny noise, and then something flew out and smacked me in the face.  Further checking showed that my 2002 tax return was missing.  This was the heaviest file on my system, and I can only conclude it must reached the edge of the disk and achieved terminal velocity.
    [/quote]

    Don't you mean Escape Velocity?

    [/quote]

    No, "terminal" is right, since it sounds like the data did its level best to kill him.



  • [quote user="EddiePedant"]Newton's Laws are only valid in an inertial frame.  A rotating frame of reference is therefore not "every bit as valid" as an inertial one.[/quote]

    Who said anything about Newton's Laws? I certainly didn't. The fact that Newton's Laws don't apply doesn't change the fact that it's still a valid force in that frame. Some different set of laws will apply, to that frame and that frame alone.

    And we'll ignore the fact that Newton's Laws are actually incomplete, in any frame. :)



  • Damn small edit timelimits!

    [quote user="EddiePedant"]But, if we wanted to calculate in this 2g frame a lot, we might just
    use this "anti-gravity" pseudo-force to make our calculations a bit
    easier.  Would "anti-gravity" be any more real then?[/quote]

    Depends on your definition of "real". Who says that an inertial frame is more "real" than a non-inertial one anyway?

    All
    frames are equally valid. You cannot preferentially choose one frame
    over another. Yes, you can easily generalize a set of laws for the set
    of inertial frames, but that doesn't doesn't make non-inertial ones
    into pseudo-frames and it doesn't make forces in those frames into
    "pseudo-forces" either.

    What if that box dropping at 2g had no
    windows? What if you had no other frame of reference to compare it to?
    How would you know your frame was not "real"?



  • [quote user="EddiePedant"][quote user="Thanny"]

    There's no such thing as centripetal force.

    [/quote]

    I think you mean there's no such thing as centrifrugal
    force.  It's officially a pseudo-force.  The centripetal
    force is a real force (i.e. it is not just a product of the rotating
    coordinate system, as the centrifrugal pseudo-force is).

    [/quote]

    Acceleration,
    not force.  I was sure someone would know their physics well
    enough to pick up on it, but even friggin' Wikipedia has the entry on
    centripetal acceleration labelled as "Centripetal force".

     



  • [quote user="Thanny"]Acceleration,
    not force.  I was sure someone would know their physics well
    enough to pick up on it, but even friggin' Wikipedia has the entry on
    centripetal acceleration labelled as "Centripetal force".[/quote]

    Acceleration does not occur until a force is applied. Centripetal acceleration is caused by rotation. We'll call it "Centripetal force".

    An article called "Gravitational Acceleration" would be silly.

    Would you prefer "Rotational Outward Force"?



  • [quote user="dhromed"]

    [quote user="Thanny"]Acceleration,
    not force.  I was sure someone would know their physics well
    enough to pick up on it, but even friggin' Wikipedia has the entry on
    centripetal acceleration labelled as "Centripetal force".[/quote]

     

    Acceleration does not occur until a force is applied. Centripetal
    acceleration is caused by rotation. We'll call it "Centripetal force".

     An article called "Gravitational Acceleration" would be silly.

    Would you prefer "Rotational Outward Force"?

    [/quote]

    I'd prefer everyone have more knowledge of high-school level physics. 



  • [quote user="Thanny"]

    I'd prefer everyone have more knowledge of high-school level physics. 

    [/quote]

    Well okay.

    But that stuff is forgotten easily unless you actually do physics, so please forgive The Poor Humans.

    I had to make an effort to calculate the final speed of a body hitting a floor in earth gravity after t seconds.

    I rediscovered 1/2at^2 by accident, and finally understood the things that I got Fs on back in highschool. :3 



  • [quote user="dhromed"][quote user="Thanny"]

    I'd prefer everyone have more knowledge of high-school level physics. 

    [/quote]

    Well okay.

    But that stuff is forgotten easily unless you actually do physics, so please forgive The Poor Humans.

    I had to make an effort to calculate the final speed of a body hitting a floor in earth gravity after t seconds.

    [/quote]

    That's easy: You simply integrate acceleration with respect to time.



  • [quote user="Bert"]If the bits fall off the edgeof the disk, should one put a container under the disk to catch them. If so can we call it the bit bucket? Will we have to empty said bit bucket?[/quote]

    No need.  Just let it all pile up and you can store information on the heap.  If you're really tidy, you can end up with a stack instead. 


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