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

Starting with a look at steady-state performance, the 750 EVO is clearly inferior to the 850 EVO, particularly at 250GB. But it outperforms most of the planar TLC competition and the occasional low-end MLC drive.

Steady-State 4KB Random Write Consistency

The high consistency score is a hallmark of Samsung's top-notch controller architecture. The 750 EVO is in an entirely different league from the planar TLC drives.

IOPS over time
25% Over-Provisioning

The 750 EVO's initial burst of high performance is relatively short-lived, but it transitions into a very well-regulated steady state. The gradual performance recovery before a second smaller drop in performance is less pronounced than on the other Samsung drives, but is still present.

With extra overprovisioning, the 750 EVO's steady state shows much looser performance regulation but is still delivering a better worst-case than its competition's best-case.

Steady-State IOPS over time
25% Over-Provisioning

A closer look at the 750 EVO's steady state is pretty boring, with no clear patterns of periodic background maintenance or sporadic outliers.

Introduction, The Drive & The Test AnandTech Storage Bench - The Destroyer
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  • ewitte - Tuesday, May 24, 2016 - link

    System builders will likely go even cheaper there are a lot of 240GB drives around $60. Nearly a $20 difference.
  • Murloc - Saturday, April 23, 2016 - link

    They're going to put it into computers and write "Samsung SSD inside" and it will be cheaper for the system builders, but the average customer will not be able to tell the difference.

    So yes, it's a winner.
  • lilmoe - Friday, April 22, 2016 - link

    You think $10 is worth the downgrade? Bruh...
  • 5th element - Friday, April 22, 2016 - link

    To the 3rd party selling complete machines to the everyday masses yeah. Like haukionkannel said above. Most people out there aren't tech heads and the lower £££ matters.
  • lilmoe - Saturday, April 23, 2016 - link

    Sure, but the price difference is even lower with higher volume...
  • nathanddrews - Friday, April 22, 2016 - link


    Thanks for the great review - as always. The "meh" is just for the drive itself.
  • nathanddrews - Friday, April 22, 2016 - link

    The problem I have with SSDs right now is that they're so boring to me. What I need in my life are consumer grade NVMe 2TB+ SSDs. I'm sick and tired of buying multiple SSDs or splitting my application and data across SSDs and HDDs. One drive to rule them all, please.
  • TheinsanegamerN - Friday, April 22, 2016 - link

    We should probably work on getting 1TB drives out and purchasable before worrying about 2TB models.
  • vanilla_gorilla - Friday, April 22, 2016 - link

    Samsung 850 EVO 1TB SSD are $291 on Amazon (Prime) right now. And the Samsung 850 EVO 2TB is the same price per gigabyte ($600 for 2TB).
  • Meteor2 - Friday, April 22, 2016 - link

    I don't know about 2+ TB but definitely more 1 TB NVMe drives. SATA is yesterday's tech.

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