PROPER Sandisk Extreme HD Video 16GB SDHC card tests (a.k.a, update your card readers!)

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  llama on 02/02/2012 - 02:10

  if you buy a high speed card and complain about the speeds, you need a better reader. Especially if your max speed happens to be 15 to 20MB/s!

  Yeah, but that is mainly because the absolute maximum speed of USB 2.0 is well under 30MB/sec, and many motherboards give about 20MB/sec

  It's the same thing as with Portable Hard Drives - I have a 3.5" 7200rpm drive here that gets 90MB/sec in a USB 3.0 dock, but the same dock in a USB 2.0 port gives about 22-27MB/sec.

  Good speeds on those Extreme cards = Class 30 FTW!! I didn't grab them because they were full SD and I have made a personal "pact" to only buy MicroSD from now on, so I can use them in all my devices (rather than just the camera).

  PS - could you please get rid of the https in the URLs, it causes browsers to give a warning and block access (due to some page elements being http, whilst the URL is https)

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    _Bruce_ on 02/02/2012 - 08:29

    You need a better reader.

    Be careful here. You need a SATA/PCMCIA/USB3/Firewire/PCI reader, not USB2. The readers are very simple devices and in all most all cases 'quality' of the reader will make no difference.

    the absolute maximum speed of USB 2.0 is well under 30MB/sec

    Not technically true, the maximum is 60 MB/sec, but this has to be shared across all devices and there are many reasons why this rate cannot be sustained.

    Edit: To clarify, first quote is the OP.

    • 

      llama on 02/02/2012 - 11:05

      the absolute maximum speed of USB 2.0 is well under 30MB/sec

      Not technically true, the maximum is 60 MB/sec, but this has to be shared across all devices and there are many reasons why this rate cannot be sustained.

      You realise that USB 2.0 is a maximum of 480Mbits/sec? There are 8 bits per byte, but you are forgetting the communications protocol overheads etc

      READ > http://en.wikipedia.org/wiki/Universal_Serial_Bus#Transmissi…

      And with HDD or Flash drives, there is some additional erorr checking that goes on.

      ANyway, I will reword it to…

      The maximum REAL-WORLD throughput of USB 2.0 is well under 30MB/sec when Writing, although many drives may benchmark faster in "Read" tests.

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        _Bruce_ on 02/02/2012 - 11:13

        You realise that USB 2.0 is a maximum of 480Mbits/sec? There are 8 bits per byte

        Which is 60, as noted.

        you are forgetting the communications protocol overheads etc

        Actual protocol overheads are very minimal, the biggest issue is the shared bus and interrupt handling which means:
        1: All bandwidth is shared between devices.
        2: Speed in acheived in bursts and rarely for long enough to be considered so high for sustained transfers.
        This is as I stated above.

        READ > http://en.wikipedia.org/wiki/Universal_Serial_Bus#Transmissi…

        Confirms all statements I am making.

        And with HDD or Flash drives, there is some additional erorr checking that goes on.

        This is nothing to do with USB, and is between the drive firmware and the storage medium. In these cases change bus will not help you at all.

        The maximum REAL-WORLD throughput of USB 2.0 is well under 30MB/sec when Writing, although many drives may benchmark faster in "Read" tests.

        Still missing the point, write and read makes no difference to USB, write is slower because the storage device is slower on write. Some benchmarks will give you higher numbers than file transfer because:
        1: They use short bursts which may achieve close to the maximum throughput instantaneously.
        2: They are reading from cache on the device rather than the full storage on the device if the same data is read repeatedly.

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        llama on 02/02/2012 - 11:43

        For GAWD'S SAKE… http://en.wikipedia.org/wiki/Semantic_dispute

        This thread is not discussing the USB protocol, it is about the STORAGE DEVICES that just happen to use that protocol.

        OK, whilst it is overly complicating a very simple statement… I will reword it YET AGAIN to…

        The maximum data throughput that most people will experience from USB 2.0 STORAGE DEVICES in the REAL-WORLD is well under 30MB/sec when Writing, although many drives may benchmark faster in "Read" tests.

        This speed limitation is the result of the combination of the USB Protocol restrictions, device controllers, data checking, the device itself, plus approximately 3,652,192 other known variants. But it will be close enough for the purposes of GENERAL DISCUSSION.

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      toomuchdogfur on 02/02/2012 - 12:53

      Fixed to be more specific about card reader recommendations. Though I only put in USB3 and PCI-E because:
      - SATA: Tbh I have never heard of a SATA card reader
      - PCMCIA (and Expresscard): There are many laptops which actually have these readers connected to an internal USB2.0 port (like my Lenovo x200) OR card readers for these interfaces that operate in USB2-only mode so they might not get awesome speeds anyway
      - Firewire: The fastest widespread Firewire standard is 800Mb/s = 100MB/s theoretical. USB2 struggles to achieve even a third of its theoretical max of 60MB/s, so even Firewire 800 could bottleneck faster CF cards (But NB: I am not a Firewire expert)

      • 

        _Bruce_ on 02/02/2012 - 12:56

        PCMCIA is actually very similar to CF, so for CF cards they pretty much connect straight into PCMCIA.
        Firewire is a very different beast is USB2, and even Firewire 400 will leave USB2 in the dust on real world data transfer.

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    toomuchdogfur on 02/02/2012 - 12:44

    Yeah that's what I meant, that people have got to move off USB2 if they want better speeds, but I acknowledge that I wasn't that clear - changed the post slightly for clarification.

    Fixed the https links - dunno why imgur gave me those.

    But yeah the post was mostly to show that the cards were faster than people keep saying/theorizing - I'm quite surprised that they exceeded their own marketing department claims!

    • 

      llama on 02/02/2012 - 13:16

      if you buy a high speed card and complain about the speeds, you need a better interface + card reader - USB3.0 or PCI-E

      Might be best to say something like "… USB3.0 card reader connected to a USB 3.0 port. Only modern motherboards have USB3.0 headers, so if yours doesn't then you also need to get a PCI-e USB3.0 add-on card.

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  BuyoTheCat on 02/02/2012 - 12:10

  I would want to buy a high speed card for use on my camera. (for video or still)
  because, I do not want the camera buffer to fill up so quickly so that I can keep shooting.