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  1. #1
    Gold Lounger Maudibe's Avatar
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    Hey fellow loungers,

    When I am transferring files from primary HDD to external USB 2.0 HD the transfer time is fairly long. USB transfers are rated up to 480 Mbps (megabits per second) however, my typical transfer of a 2 GB (gigabyte) file is around 2 min 20 sec. Doing the math, 2 GB over 140 sec= 0.014 GB/s. Multiplying by 8 = 0.112 Gb/s (gigabits per sec). Multiplying by 1000 = 112 Mbps (megabits per second). This is approximately 1/4th the speed of USB max ratings. To ensure that I am getting optimal speed, I have ensured that both HDD and ext HDD are defragmented. I have also tested the transfer rates with no background tasks running. I have 4GB memory installed on an XP SP3 system (32bit), 2.8 Ghz Duo Core CPU and plenty of HDD space on both drives. My HDD spindle speed is 7200 w/ 32 MB buffer while the ext HDD is a Western Digital My Book Essential w/ the same specs. The same speed is calculated for files as low as 1 GB; it would be inaccurate to test smaller files since they would be more sensitive to timing (human) errors.

    Any thoughts on why my transfer rates may be limited or how to speed them up?
    Thanks, Ted

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    5 Star Lounger chowur's Avatar
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    Try plugging your external HD in the back of your tower instead of the front.This way your hook up is directly into the mother board.Because the USB ports Which is directly mounted on the Mother board is much faster than one in the front.
    Problems cannot be solved by the same level of thinking that created them. -Albert Einsten

  3. #3
    2 Star Lounger
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    From EverythingUSB:

    Additional notes from Alex Esquenet - our engineer friend based in Belgium: "A fast usb host can achieve 40 MBytes/sec. The theorical 60 MB/sec cannot be achieved, because of the margin taken between the sof's (125 us), so if a packet cannot take place before the sof, the packet will be rescheduled after the next sof. On top of that, all the USB transactions are handled by software on the PC. For instance, a USB host on a PCI bus will send or receive the data via the PCI bus; the stack will prepare the next data in memory and receive interrupt from the host."

    I also remember reading about problems with the My Book series of HDs, but can't remember the specifics.

  4. #4
    Super Moderator Deadeye81's Avatar
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    Hi Ted,

    Many users never experience 40 megabytes per sec. transfer rates with USB 2.0. While 60 is theoretical, everything must be really up to par to obtain as high as 40. For what it is worth, your experience is not uncommon.

    Check you BIOS to be sure your USB is set for high speed use. Also it would be worthwhile to update your motherboard chipset drivers, as well as upgrading your BIOS.
    Deadeye81

    "We make a living by what we get, we make a life by what we give." Sir Winston Churchill

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    Gold Lounger Maudibe's Avatar
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    Good points and suggestions. Although I am already using the USB ports directly connected to the mobo, I will try updating the BIOS. Thanks for your inputs!

  6. #6
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    Quote Originally Posted by Ted Fanelli View Post
    Good points and suggestions. Although I am already using the USB ports directly connected to the mobo, I will try updating the BIOS. Thanks for your inputs!
    Ted, you did not mention how long you have done USB data transfers, but all equipment begins to lose its performance specs over time. In my case, I did whole-system image backups of 100-110GB routinely in approximately 120 minutes. That happy routine became noticeably slower over time until my "overnight" imaging sessions were still unfinished next morning-- some 12 hours later. The culprit was probably a USB ext HD enclosure port adapter board that fell out of spec and imposed time-consuming (automated) corrective measures. Put another way, and barring problems with defective cabling or faulty source drives, your slowdown comes from either the USB ext HD enclosure or the enclosure HD itself.

    As an experiment, try to isolate the HD from the enclosure by installing the HD on the IDE primary, and doing the same operation. Yes, speed will improve dramatically, but this also will tell you more about the HD, if it does not. Alternately, put a known good drive in the enclosure, and do the same operation. At some point, you will discover whether the enclosure / port or the HD, itself, is the source of delay.

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