Extremely slow transfer speed from external HD to Macbook

Discussion in 'Mac Basics and Help' started by Wisconsin, Apr 23, 2009.

  1. Wisconsin macrumors newbie

    Apr 23, 2009
    This ended up being pretty long but I tried to include as many details as possible. If any more information is needed please just let me know in this thread.


    Hey everyone I have been trying to figure this out all day and it has been driving me nuts. I would really appreciate it if you guys could help me figure out what is going on here.

    First of all I have a Macbook with a 2.4GHz Intel Core 2 Duo processor, 4 GB of RAM and am running Mac OS X Version 10.5.6. Also this is the last generation of the "white" macbook that came out in February I believe of last year.

    My external HD is a 1TB Rock Mobile Disk.

    For some reason when I try to transfer files to or from the external HD to my Mac I am getting nowhere near the expected 480MB/s. I do use a Swiss Gear 4-port USB splitter. When I use the splitter I am getting a transfer rate of about 120MB/s and without it I am only getting about 300MB/s. This is of course if I am only trying to transfer one 800MB movie. If I attempt to transfer multiple seasons of television shows it will drop to as low as 40-50MB/s.

    Also, if I were to be transferring a single season of a TV show. The transfer speed is much faster to click and drag every episode from my HD to my Mac than it is to transfer the entire folder at once. The whole folder might take 25 minutes but one at a time it will only take about 5.

    This really is annoying and if anyone can help me out with this it would be greatly appreciated.
  2. madog macrumors 65816


    Nov 25, 2004
    Korova Milkbar
    A High-Speed (USB 2.0) has a rate of 480 Mbit/s (60 MB/s). All high-speed devices are capable of falling back to full-speed operation if necessary (USB 1.0 speeds of 12 Mbit/s (1.5 MB/s)).

    480 is essentially the maximum speed under optimal conditions, and is rarely ever seen in real world transfers. In fact, FireWire 400, while technically with a slower top speed, is consistently faster in real world transfers. So USB 2.0, under the best conditions, would transfer a 120MB file in 2 seconds though in reality it will probably take 3-5 seconds.

    Also, as you noticed, when you have a hub or something else in the way it can lower speeds quite a bit. After that, not all USB/FW devices (and hard drives within) are created equal. You can have two different ones from different manufacturers that are listed with the same specifications yet one could outform the other (though typically not by much).
  3. The General macrumors 601

    Jul 7, 2006
    UBS 2.0 = <480 megabits per second. There are 8 megabits in 1 megabyte. USB 2.0 can theoretically transfer at most 60 megabytes per second. You say you got 300MB/s, which is basically LUDICROUS SPEED even on eSATA.
  4. Wisconsin thread starter macrumors newbie

    Apr 23, 2009
    Yeah after looking at this I went back and did the math. It was way wrong. But the speed still makes me want to blow my ****ing brains out. It is not going anywhere near where it should.

    Anyway, thanks for all of the help guys.

    David Brown

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