How We Test HDDs And SSDs

Steady State

Steady state performance is often associated with enterprise workloads. For the most part, that is where I think it can stay. Client SSDs spend most of their time idling. The TRIM command, garbage collection and wear-leveling schemes have a chance to clean the NAND cells, which are kept ready for fresh writes.

The two images above are what we've come to associate with steady state performance. In a client environment, you never write 4KB blocks to your SSD for hours at a time. The first chart shows the second pass, not even the initial pass with clean cells available to absorb the write load. The second chart is what we are most interested in looking at. It illustrates your span of random performance in a worst-case scenario. Ideally, you'll see high IOPS throughput and a consistent flow of data, without much deviation. 

There are some instances when steady state performance data is more relevant, such as prosumer workloads. Sequential mixed workload steady state testing shows us how a drive behaves after heavy multimedia editing on a secondary drive. Since we don't know what everyone's typical mix is, we show everything from 100% read to 0% read (which is 100% writes).

Chris Ramseyer
Chris Ramseyer is a Contributing Editor for Tom's Hardware US. He tests and reviews consumer storage.
  • 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