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How We Test HDDs And SSDs

Product Specifications

Companies publish specifications based on out-of-box performance data. The type of information given to the public varies from one manufacturer to another. Even the way specs are generated is not standard. The general rule is four-corner performance: sequential reads, sequential writes, random reads and random writes.

Two methods for determining sequential performance come from easy-to-use software with a GUI interface. ATTO at a queue depth of four or 10 is the old-school method. The utility won't let you test with a single outstanding command though, reporting throughput numbers not often seen in the real world. SanDisk and a few other companies no longer use ATTO and instead prefer CrystalDiskMark to show sequential read and write performance.

Random IOPS can be measured a number of ways. Most companies use Iometer with 4KB blocks at a queue depth of 32. Again, the results appear impressive, but share very little with the drive's real world behavior. We'll go into more depth on this shortly.

There are a few things to keep in mind when it comes to the specifications found on manufacturer websites and product packages. We've already touched on real-world performance and how you shouldn't expect to get relevant data from the company selling you its drive. After all, a typical use case doesn't exist. Even on the same machine, workloads vary from data to day. You especially can't compare one vendor's specs with another's. They use different configurations to generate their data, introducing variance.

  • 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