Why does it take longer to transfer data from an SSD to a flash drive than from a flash drive to a HDD?

So I have a big HDD on an old laptop, and I use that for backing up some data. My new laptop has an NVME SSD, but it’s small, so I like to transfer big files off of it. I usually copy the large files from the SSD laptop to a 64 Gb USB 2.0 flash drive. To my surprise, the transfer speed for these large files is around 3-5 MB/s. But transferring the files from flash to the HDD is around 10-15 MB/s. Why is this happening? The SSD is capable of a far higher read and write rate than the HDD. So maybe the speed of the drive isn’t relevant? I thought when transferring data between devices, you had to take both device speeds into account. I’m guessing in this situation I’m dealing with a misconception of read and write speeds. I know reading is faster than writing and reading is the speed to load something while writing is the speed to save something. But I don’t see how writing to a HDD is faster than writing to flash from an SSD. Thanks in advance.

2 Answers

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  • 1 month ago
    Favorite Answer

    Because you are writing to the flash drive when copying from the SSD, and only reading from it when you copy to the hard drive. Writing to flash is a slower operation than reading. You would see exactly the same thing copying from the hard drive to the flash drive, or from the flash drive to the SSD. There's no mystery here.

    • Jason
      Lv 4
      1 month agoReport

      Thanks a lot!

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  • keerok
    Lv 7
    1 month ago

    The write speed of the flash drive is much slower than that of an HDD.

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