Re: Transfer rates of external USB 2.0 hard drive - OS2

This is a discussion on Re: Transfer rates of external USB 2.0 hard drive - OS2 ; Forget about the marketing numbers. This is the theoretical speed limit of the bus when doing bidirectional transfers. So half the speed for unidirectional operation and you get 240 Mbit/sec for one direction. As we're talking about bits per second ...

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Thread: Re: Transfer rates of external USB 2.0 hard drive

  1. Re: Transfer rates of external USB 2.0 hard drive

    Forget about the marketing numbers. This is the theoretical speed
    limit of the bus when doing bidirectional transfers. So half the
    speed for unidirectional operation and you get 240 Mbit/sec for
    one direction.

    As we're talking about bits per second here, we get a theoretical
    transfer rate in one direction of 30MByte/sec (240 Mbit/sec / 8).
    As there is some protocol overhead for maintaining the USB connection,
    you will never get more than 29-29.5MByte/sec with USB 2.0 Highspeed.
    This is also what chipset tests show.

    My external USB 2.0 Highspeed disk (300GB TrekStor) achieves a
    realistic transfer rate of 27-28MByte/sec under Win XP with
    NTFS->NTFS and large files.
    On eCS with the latest USB drivers the transfer rate is only
    marginally less than this, it's around 27MByte/sec with JFS.
    With FAT32 on eCS it's very, very slow, less than 2MByte/sec.
    So this is useless for transferring much data.

    As others noted already, the overhead increases with the file/size
    ratio. The smaller the files the higher the overhead compared to
    the file data.

    So it's not the fault of the drivers or the hardware.

    If you get much lower transfer rates, check that in BIOS the
    USB 2.0 Highspeed mode is enabled. Also try to connect the drive
    to an other USB 2.0 port. To get the highest speed, you should
    ensure that this port is not shared with other devices (via hub
    for instance). Otherwise the bandwidth is shared between these devices.
    In Win XP you can see the devices using the same physical USB port
    in the Hardware Manager (open the USB port icons). I thin on OS/2
    the USB Resource Manager also shows the physical port of devices.

    Hope that helps.

    > I'm confused because the SimpleTech documentation states that a USB 2.0
    > connection could yield transfer rates "up to 480 Mb/sec" (and 12 Mb/sec
    > for USB 1.1). Note the lower-case "b" in "Mb/sec" - I don't know if they
    > mean bits or bytes. If they mean bits and "M" means 1,000,000, then:
    >
    > 480,000,000 / 8 = 60,000,000 = 58,593.75 KB/sec
    >
    > which is much faster than my results.
    >
    > If they mean bits and "M" means 1024 * 1024, then:
    >
    > 480 * 1,048,576 / 8 = 62,914,560 = 61,440 KB/sec
    >
    > And, if they mean megabytes (not megabits) then their claim is even more
    > out of line with my results:
    >
    > 480 * 1,048,576 = 503,316,480 = 491,520 KB/sec


  2. Re: Transfer rates of external USB 2.0 hard drive

    [A complimentary Cc of this posting was sent to
    Heiko Nitzsche
    ], who wrote in article <45fbeca0$0$6398$9b4e6d93@newsspool2.arcor-online.net>:
    > As we're talking about bits per second here, we get a theoretical
    > transfer rate in one direction of 30MByte/sec (240 Mbit/sec / 8).


    Can't be so. People measure 33MB/sec transfers in real-life
    situations; see http://www.barefeats.com/usb2.html.

    But there is some major flaw in USB2 design-or-implemenation - "about
    1/2 of the maximum" is what people typically observe...

    > marginally less than this, it's around 27MByte/sec with JFS.
    > With FAT32 on eCS it's very, very slow, less than 2MByte/sec.


    My experience of efficiency of os2's FAT32 is about 6% of the channel
    throughput. So it supports this number.

    > So this is useless for transferring much data.


    "Useless" is a very strong word. I participated in a transfer of more
    than 200GB of data through USB1 to a FAT32 drive. A couple of weeks,
    and it is there! ;-)

    Hope this helps,
    Ilya

  3. Re: Transfer rates of external USB 2.0 hard drive

    >> On eCS with the latest USB drivers
    >
    > Which are? I have:
    > 12-21-05 14:13 23,386 usbd.sys
    > 12-21-05 14:14 42,112 usbehcd.sys
    > 12-21-05 14:14 41,984 usbmsd.add
    > 12-21-05 14:14 35,532 usbohcd.sys
    > 7-10-06 4:28 32,326 usbresmg.sys


    Yeah, based on the file sizes yours seem to be the same ones.

    bldlevel usbd.sys -> 10.162
    bldlevel usbehci.sys -> 10.162
    bldlevel usbuhcd.sys -> 10.162
    bldlevel usbmsd.add -> 10.162
    bldlevel os2dasd.dmd -> 14.104

    > In case it matters, follows are the USB related entries in CONFIG.SYS:
    >
    > BASEDEV=usbehcd.sys /V
    > BASEDEV=usbohcd.sys /V
    > BASEDEV=usbohcd.sys /V
    > BASEDEV=usbd.sys
    > BASEDEV=usbmsd.add /V /FLOPPIES:0 /REMOVABLES:3
    > DEVICE=C:\OS2\BOOT\usbresmg.sys /V


    I have a VIA K8T800 chipset with 8237 southbridge (Athlon64)
    and thus use the UHCI driver.

    Some older nVidia chipsets were known to have lousy USB throuput
    but I can't remember which ones.

    >> As others noted already, the overhead increases with the file/size
    >> ratio. The smaller the files the higher the overhead compared to
    >> the file data.

    >
    > Please see my recent message to Ilya - while increasing the filesize
    > increases the transfer rate I'm still not getting close to the numbers I
    > should be getting (whether under eCS or XP).


    Well, this really sounds as a hardware issue as also your
    XP makes it not faster.

    >> If you get much lower transfer rates, check that in BIOS the
    >> USB 2.0 Highspeed mode is enabled.

    >
    > There exists no option in my BIOS with that precise designation. There
    > is a "USB Controllers" setting, with the following options: "V1.1+V2.0",
    > "V1.1", and "NONE". Of course, I have it set to the first of these.


    What chipset is this?

    Are you sure that it really supports USB 2.0 Highspeed mode
    and not just Fullspeed? Simply "USB 2.0" says nothing about the
    supported transfer rate. Usually Highspeed capable devices and
    controllers have a separate logo (USB 2.0 Highspeed).

    If the board only supports Fullspeed mode (12MBit/sec max.) you can
    try with an add-on USB card that supports USB 2.0 Highspeed mode.
    Even though I haven't done this, the USB driver readme says that
    you need a card that has an UHCI/OHCI AND EHCI compatible chipset.

    BTW, did you ever got a faster transfer rate with any other device
    (e.g. a card reader)? Even my CF card reader with a SanDisk Ultra II
    card easily achieves 6MB/sec when reading and more than 3MB/sec when
    writing.


  4. Re: Transfer rates of external USB 2.0 hard drive

    > How would I find out if mine is one of them? (though, it's not really
    > "old".)


    I don't think the nForce2 Ultra 400 is one of them.

    > We're getting a little beyond my level of expertise here (e.g., I don't
    > know what "Northbridge" and "Southbridge" refer to), but the
    > specifications summary of the motherboard manual states:


    The northbridge mainly maintains the AGP bus and memory transfers
    between CPU and RAM while the southbridge is the IO chip for most
    of the device ports like USB, LAN, Audio and also PCI cards.

    >> If the board only supports Fullspeed mode (12MBit/sec max.) you can
    >> try with an add-on USB card that supports USB 2.0 Highspeed mode.
    >> Even though I haven't done this, the USB driver readme says that
    >> you need a card that has an UHCI/OHCI AND EHCI compatible chipset.

    >
    > I came across the SIIG USB 2.0 4-Port Bay Hub:
    >
    > http://www.siig.com/product.asp?pid=577
    >
    > which I may get if I can determine that (for whatever reason) my current
    > hardware is incapable of rates faster than I'm getting.


    This is just a hub, not a controller card. It uses the same
    on-board USB ports via cable. So it would not make any difference.

    This is for instance a controller card:
    http://www.siig.com/product.asp?pid=305&catid=18
    (the USB 2.0 highspeed logo is below the card picture)
    Don't know if it would work. It is just an example.

    >> BTW, did you ever got a faster transfer rate with any other device
    >> (e.g. a card reader)? Even my CF card reader with a SanDisk Ultra II
    >> card easily achieves 6MB/sec when reading and more than 3MB/sec when
    >> writing.

    >
    > I'm unsure of what you're asking here. My recent post to Ilya included
    > the following:
    >
    > Elapsed Bytes Filesize Xfer rate
    > (secs) (GB) Files avg. (MB) (MB/sec.)
    >
    > SimpleDrive (JFS->JFS) 9,585 61.08 7,915 7.90 6.53
    > SimpleDrive (JFS->JFS) 997 9.67 114 86.86 9.93
    > SimpleDrive (JFS->JFS) 210 1.41 1 1,443.84 6.87
    > Voyager (JFS->HPFS) 190 1.41 1 1,443.84 7.61
    >
    > ("Voyager" is a Corsair Voyager 4 GB flash drive formatted as a single
    > HPFS partition for its entire capacity)


    Sorry, I have somehow missed this info. This changes the picture a lot.

    The transfer rate for the flash drive looks fine. It is realistic.
    So a different controller card would not help. Your ports and drivers are fine.

    It seems more that the SimpleDrive and your USB controller don't like
    each other or the disk drive is simply not faster (which I doubt).

    Can't you test with a different hard disk borrowed from a friend?
    Maybe try it on XP first (as it also is impacted) if he has no OS/2.


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