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How We Test HDDs And SSDs

Four-Corner Testing

The basic four corners of storage testing include sequential reads, sequential writes, random reads and random writes. Not every reviewer or company tackles these the same way.

Sequential data is usually measured with 128KB blocks, though some editors like to use 64KB and others go as high as 8MB blocks. For the most part, we use 128KB, but also publish a single-drive chart that shows a range of block sizes from 512b to 8MB in both sequential and random workloads. This chart also shows queue depths between one and 32.

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Random data performance is almost universally measured with 4KB blocks at a queue depth of 32. This metric shows what manufacturers want end users to see, though it doesn't accurately reflect real-world performance. We show random performance with 4KB blocks at several queue depths ranging from one to 32 for most devices. PCIe-based products scale well past this queue depth, so we go as high as 128 in some tests.

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In each review, we show a comparison between sequential reads and writes at a queue depth of two. We also break random read performance into groups on a bar graph at each queue depth. These random 4KB charts are divided into high and low queue depths.

  • damric
    How I test an SSD. HARD RESET my computer 20 times. If the SSD is still recognized by the motherboard, then the SSD controller is worth a flip.

    SSDs will never wear out due to IOPs. Only the controllers break. Quit kidding yourselves.
    Reply
  • schizz69
    Great article. Always good to get a glimpse inside the process, which Tom's is always so willing to do.
    Thanks Chris.
    Reply
  • ssdpro
    You'll notice all these review sites keep their tests nice and short. That way Samsung stays happy and keeps buying ad space. If they tested a drive months apart Samsung would be exposed with those floppy disk slow reads.
    Reply
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  • Gurg
    None of these tests give the consumer any indication of the degredation of the performance of the SSD over time. While my systems have been become more powerful and the software has been updated, the performance of my main SSD used mostly for for W7 and hardware drivers and as measured by Passmark runs has declined by 38% in about three years.
    Reply
  • unityole
    @Gurg, as SSD over time, either via temperature or usage or amount of data filled performance declines. if you secure erase and install new window and it'll back to brand new performance again, tbh i think this article cover most of it, maybe you're just confused between a good ssd or uncleaned window files slowing down your system.
    Reply
  • ykki
    How I test an SSD. HARD RESET my computer 20 times. If the SSD is still recognized by the motherboard, then the SSD controller is worth a flip.

    And that will be all on your first day of "How to test hardware the MacGyver way"

    Tomorrow we will learn to test psu's by putting them in microwave at 50 degree C for 60 minutes while it itself is powering the microwave.
    Thank you. :lol:

    Reply
  • damric
    15491425 said:
    How I test an SSD. HARD RESET my computer 20 times. If the SSD is still recognized by the motherboard, then the SSD controller is worth a flip.

    And that will be all on your first day of "How to test hardware the MacGyver way"

    Tomorrow we will learn to test psu's by putting them in microwave at 50 degree C for 60 minutes while it is powering the microwave.
    Thank you. :lol:

    I choked on my drink you had me LOLing so hard :)
    Reply
  • unityole
    15491425 said:
    How I test an SSD. HARD RESET my computer 20 times. If the SSD is still recognized by the motherboard, then the SSD controller is worth a flip.

    And that will be all on your first day of "How to test hardware the MacGyver way"

    Tomorrow we will learn to test psu's by putting them in microwave at 50 degree C for 60 minutes while it itself is powering the microwave.
    Thank you. :lol:

    calm down!!
    Reply