Performance Consistency

Our performance consistency test explores the extent to which a drive can reliably sustain performance during a long-duration random write test. Specifications for consumer drives typically list peak performance numbers only attainable in ideal conditions. The performance in a worst-case scenario can be drastically different as over the course of a long test drives can run out of spare area, have to start performing garbage collection, and sometimes even reach power or thermal limits.

In addition to an overall decline in performance, a long test can show patterns in how performance varies on shorter timescales. Some drives will exhibit very little variance in performance from second to second, while others will show massive drops in performance during each garbage collection cycle but otherwise maintain good performance, and others show constantly wide variance. If a drive periodically slows to hard drive levels of performance, it may feel slow to use even if its overall average performance is very high.

To maximally stress the drive's controller and force it to perform garbage collection and wear leveling, this test conducts 4kB random writes with a queue depth of 32. The drive is filled before the start of the test, and the test duration is one hour. Any spare area will be exhausted early in the test and by the end of the hour even the largest drives with the most overprovisioning will have reached a steady state. We use the last 400 seconds of the test to score the drive both on steady-state average writes per second and on its performance divided by the standard deviation.

Steady-State 4KB Random Write Performance

The 960 EVO's steady state random write speed is not quite as fast as the 960 Pro, but it's in the same league and much faster than most consumer SSDs.

Steady-State 4KB Random Write Consistency

The 960 EVO sets a new record for combining high performance with consistency. It's a bit slower than the 960 Pro, but less variable.

IOPS over time
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25% Over-Provisioning

Highly consistent performance is a good thing, but it makes for a boring graph. The transitions from peak to sustained performance modes look the same for both the 960 Pro and the 960 EVO.

Steady-State IOPS over time
Default
25% Over-Provisioning

The 960 EVO responds to extra overprovisioning with even more consistent (and high) performance.

Introduction AnandTech Storage Bench - The Destroyer
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  • SaolDan - Tuesday, November 15, 2016 - link

    Neat! Reply
  • jwhannell - Tuesday, November 15, 2016 - link

    Do want Reply
  • nathanddrews - Tuesday, November 15, 2016 - link

    can haz Reply
  • edward1987 - Friday, December 02, 2016 - link

    I've never seen such a demand for nvme ssd like samsung 960 evo. They are sold only on preorders basis. Looks like the only available capacity is 250GB https://www.span.com/search/960_space_evo/-Samsung Reply
  • EKFxWtB - Wednesday, November 16, 2016 - link

    Yea! Reply
  • yankeeDDL - Tuesday, November 15, 2016 - link

    The 960 EVO is today, what the 850 EVO was a couple of years ago. Buying anything else makes little sense.
    The 850 EVO is still today an excellent SSD with a fantastic price/performance ratio.
    I am happy to see such impressive improvements: I only hope we don't need to wait 2 years to see some worthy competitor ...
    Reply
  • Ninhalem - Tuesday, November 15, 2016 - link

    Only if you have 480 USD to spend on a 1 TB SSD. If you don't (and many people don't need those read/write speeds), then something like the Mushkin Reactor 1 TB can be had for half the cost. Reply
  • TheinsanegamerN - Tuesday, November 15, 2016 - link

    While I agree, it's a bit of apples to oranges. The reactor is a sata III SSD, not a NVMe class SSD. Compared to other NVMe drives, the 960 evo is a great performance per dollar value. Reply
  • ImSpartacus - Tuesday, November 15, 2016 - link

    I think the confusion arises from the op not specifying that he was only talking about nvme m.2 drives. Reply
  • ddriver - Tuesday, November 15, 2016 - link

    It doesn't really matter when the speed doesn't result in any tangible practical improvements. Reply

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