SSD/USB3.0 Speed Drop


  1. Posts : 579
    Windows 10
       #1

    SSD/USB3.0 Speed Drop


    When transferring files from my external SSD/USB3.0 to my PC, the speed drops from around 300MB/s to 105MB/s.
    It stays at 300MB/s almost 60% of the transfer, then it Drops.

    What to do so that there is no Drop?

    EDIT: Disabling the "Write Cache" for HDD in PC, the speed drops to around 45MB/s, instead of 105MB/s.

    SSD/USB3.0 Speed Drop-usb30-speed-drop.jpg
      My Computer


  2. Posts : 4,224
    Windows 10
       #2

    ISO files are an archive format that results from making a sector-by-sector copy of every "dirty" (written-to) sector in a storage collection. Originally developed for optical media, ISOs are used for creating containers for all kinds of information including Windows images and install environments. Typically, throughput drops during copying as the size of the individual elements drops and the number goes up. I've seen the kind of graph you show in your screencap for many ISO transfers. I can't find a definitive source to confirm this, but my best speculation is that the drop-off occurs when the contents of the ISO switches from large binary files like .wim or .esd to the thousands of small individual files you will see in a mounted Windows ISO, especially in the /sources directory and its subsidiary directories.
    HTH,
    --Ed--
      My Computers


  3. Posts : 18,424
    Windows 11 Pro
       #3

    @EdTittel,

    It seems like the OP is just copying the single ISO file itself and not extracting the contents of the file. That would be no different than copying a 2 or 3 GB WMV or AVI media file, for example. Personally, the file transfer shown in the OP looks perfectly normal to me - at least that is the way all my large file copies look like across my computers.

    At the beginning you are seeing the various cache memories involved filling up, at the end you are seeing the actual writing to the final storage location occurring.
      My Computer


  4. Posts : 4,224
    Windows 10
       #4

    Yes, another good explanation, and probably more valid than mine. Thanks!
    --Ed--
      My Computers


 

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