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This discussion relates to Technology Review's article Intel's Plan to Replace Copper Wires.

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  khairulsyahir
  

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  09/23/2009 06:25 PM

  Speed bottleneck

  I am wondering if the Light Peak will give any significant advantage for current and near-future devices, seeing that the storage and memory components in electronic devices nowadays have far less writing and reading speed? The USB2.0 boasts 400+ MB/s transfer speed, but we barely reach 10% of that speed in actual operation of an external hard drive, for example.
  
  Sure, 10GB/s sounds impressive, but will there be any useful application of it now or let's say in 3 - 5 years' time?

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  • 
    michel.jansens@ulb.ac.be
    

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    09/24/2009 04:32 AM

    Re: Speed bottleneck

    Well, actually USB2 has a raw capacity of 480Mbits/second.
    Remove the protocol overhead and you are sensibly below that number.
    Most usual 1TB SATA2 disks can saturate this connection in burst read.
    SATA2 in itself provides up to  3Gbits/sec
    That's why USB3 is coming soon.
    
    But length of cable will never beat fiber.

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    • 
      khairulsyahir
      

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      09/24/2009 09:49 PM

      Re: Speed bottleneck

      True, but still, the bottleneck remains inside the hard disk itself. How much use can we make of a 3Gbit/s connection if the read/write head inside the hard disk can only work as fast as 20 - 40MBytes/s?

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        justahick
        

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        09/25/2009 04:52 PM

        Re: Speed bottleneck

        True, but where hard disks are replaced by SSDs, such as in many racks of servers, I could see how this would increase throughput.
        Also, it should help with keeping temperature lower inside the server, which should help with reducing power and cooling costs, although the article does not mention the power requirements, which seems to be an odd omission.
        Down the road further, I'd like to see multi-wavelength photonic interconnects both between the cores in a CPU, and the memory they use.

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    rudnric
    

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    09/28/2009 02:17 PM

    Re: Speed bottleneck

    Speed Bottleneck doesnt have a clue about USB or HDDs.
    
    "The USB2.0 boasts 400+ MB/s transfer speed, but we barely reach 10% of that speed in actual operation of an external hard drive, for example."
    
    Youve got it completely wrong.  USB 2.0 is 480 megabits per second (Mbps), not megabytes(MB/s). 
    
    Mechanical HDD's have surpassed the bandwidth of USB years ago.  Even old HDD's can can hit physical read rates from the media, over 50MB/s.  Effective transfer rate of USB 2.0 is only 20-40MB/s tops due to data overhead built into USB protocols, not 60MB/s as the raw data rate of USB 2.0 would suggest. And CPU utilization is also quite high because of that protocol when at maximum data rate.

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  Silacon
  

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  09/24/2009 05:52 AM

  Laser fiber wires

  Silacon proposed to Franklin Signal four years ago using fiber optic wires to transmit signals within circuit boards. Franklin demonstrated short distance  application of the technique. 

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  Dumd
  

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  09/24/2009 10:58 PM

  [no subject]

  What I failing to comprehend is why people are turning to a very fragile product to replace copper. True, while copper is slower, it can at least BEND before it breaks. Optical fibers just break, as they are made of glass.
  
  Optical fiber is great for long distances, as you don't need repeater sites, but if you run them over with a HMMWV, they will snap in half. Ethernet on the other hand, being made of copper, can get run over, and still function, as it is a malleable material. I congratulate Intel on their ingenuity and courage to bring something new to the table, but optics and copper are probably better off the way they are utilized now.
  
  EDIT: By the way, khairulsyahir, I see where you are coming from. I have into the same problems with multiplexers. It doesn't matter how fast your pathway is (for example, a CV-FOM that runs 8192 kb/s), if the original device cannot transmit that much information that fast (an FCC-100, which runs at 2048 kb/s). I've seen it, and it is vastly redundant, unless you plan to upgrade the system, or run multiple systems through it (multiplexing multiplexers, what a laugh).

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    prlsol
    

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    09/29/2009 10:22 AM

    Re:

    I can just hear the 'Ooops!' from Intel now, 'We forgot that the cable would bend'. My guess is they have solved the fragility problem, this isn't just a tenth grade science project.

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  Gnoetic
  

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  09/25/2009 10:39 AM

  Copper shown good to 10G also

  A Silicon Valley start up, Silicon Pipe, demonstrated copper capable of 10 to 20 Gbps data rates over distances up to 1 meter at relatively low power through a differential pair by making connections direct from chip to chip or chip to connector. They also described a path to high speed memory. There was a multi-company paper presented on the technology at DesignCon a few years ago.
  
  Since copper is robust, as was mentioned, and there will be need for copper for power, ground and lower speed circuits anyway, it is uncertain of what the advantage might be. (at this time, that is...) 

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  • 
    erbium
    

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    09/26/2009 09:35 AM

    Re: Copper shown good to 10G also

    Copper introduces a delay in the signal relative to glass in fiber optics as the signal propagation is slower at the same data rate. 

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    • 
      wdbarrett
      

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      10/26/2009 12:34 PM

      Re: Copper shown good to 10G also

      The electric field travels through copper at about 75% the speed of light in free space.  Light in the fiber travels at 70% the speed of light in free space.  In reality, the propogation delay of fiber and copper are both in the range of 1 to 1.5 ns per foot.

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