Mixed Random Read/Write Performance

The mixed random I/O benchmark starts with a pure read test and gradually increases the proportion of writes, finishing with pure writes. The queue depth is 3 for the entire test and each subtest lasts for 3 minutes, for a total test duration of 18 minutes. As with the pure random write test, this test is restricted to a 16GB span of the drive, which is empty save for the 16GB test file.

Iometer - Mixed 4KB Random Read/Write

The Samsung 950 Pro never had a clear lead on the mixed random I/O test, and then the OCZ RD400 raised the bar. The 960 Pro is 22% faster than that and is alone at the top.

Iometer - Mixed 4KB Random Read/Write (Power)

The 960 Pro has power draw comparable to the SATA SSDs that are less than half the speed, and clearly lower than the power draw of the other NVMe SSDs.

Most of these drives spend at least the first half of the test below 200MB/s and bring their score up with a strong finish of fast random writes. The 960 Pro hits 200MB/s in the second phase and continues increasing throughout the test, then finishes with a random write speed that beats even the Intel SSD 750.

Mixed Sequential Read/Write Performance

The mixed sequential access test covers the entire span of the drive and uses a queue depth of one. It starts with a pure read test and gradually increases the proportion of writes, finishing with pure writes. Each subtest lasts for 3 minutes, for a total test duration of 18 minutes. The drive is filled before the test starts.

Iometer - Mixed 128KB Sequential Read/Write

The 960 Pro's mixed sequential speeds are a big jump over any previous drive, with about a 30% advantage over the OCZ RD400A and over three times the performance of any SATA drive.

Iometer - Mixed 128KB Sequential Read/Write (Power)

The 960 Pro's power consumption is about the same as the OCZ RD400 and slightly higher than the 950 Pro, so it is only about 15% more efficient than any other drive.

At the beginning and end of the test the 960 Pro appears to be thermally limited with power consumption above 4W. In the middle of the test where it is typical to see the lowest performance, the 960 Pro doesn't even come close to dropping down to SATA speeds. Its nearest competitor in performance (the OCZ RD400) has much worse performance during the early read-heavy parts of the test.

Sequential Performance ATTO, AS-SSD & Idle Power Consumption
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  • DanNeely - Tuesday, October 18, 2016 - link

    Does your mobo power the m.2 slot, or just the LEDs? Baring evidence to the contrary I'd assume it's only the latter that are getting power, and enough residual power to run a few LEDs for a minute would only give a few seconds for the 960 in its deepest power saving modes, or far less while doing writes.
  • bji - Tuesday, October 18, 2016 - link

    How does your computer know to shut down in that event? Is there a signal to the operating system from the power supply to notify it that power has been lost and that it should shut down? Because if not, all that will happen is that 1 minute more of data will be written to the drive, only to be lost when the power abruptly cuts out when the capacitors lose their charge.
  • ddriver - Tuesday, October 18, 2016 - link

    Obviously it doesn't matter if the PSU doesn't send a signal to the system, which it doesn't. It wouldn't matter even if you have an UPS that could last an hour if it can't signal the system to shut down or at least flush caches before power runs out completely.
  • noeldillabough - Tuesday, October 18, 2016 - link

    I was thinking the exact same thing ACK no battery/capacitors? I'd never turn off buffer flushing.
  • Billy Tallis - Tuesday, October 18, 2016 - link

    I agree that what you've described is what those options *seem* to mean. But the semantics behind those checkboxes are clearly very different for NVMe drives and SATA drives, and it is an outright bug for Microsoft to apply the same description to both cases. The Samsung 960 Pro is also not the only drive to severely underperform without disabling write cache buffer flushing; the 950 Pro without Samsung's driver seems to be similar and I've seen this behavior on at least other vendor's NVMe controller. This is a serious concern that requires further investigation, but I'm not ready to lay the blame on the Samsung 960 Pro. If Microsoft's defaults for NVMe drives is the most reasonable behavior for consumer workloads (including the risk of power loss), then that would imply that most or all of the vendor-specific NVMe drivers are playing fast and loose with data safety, and possibly so are Microsoft's SATA/AHCI drivers.
  • shodanshok - Tuesday, October 18, 2016 - link

    "that would imply that most or all of the vendor-specific NVMe drivers are playing fast and loose with data safety, and possibly so are Microsoft's SATA/AHCI drivers"

    This can be quite true, especially considering as some vendors publish "turbo-cached mode" that supposedly enhance disk write speed. By the way the storage controller drives is such a critical kernel component that I will try hard to stay with Microsoft own driver, unless extensive testing on vendor-specific drivers confirms their stability.
  • HollyDOL - Tuesday, October 18, 2016 - link

    Wouldn't INT 0 (power loss) fire fast enough to execute flush command in time for decent PSU to handle that before running out of power? Most of "decent+" PSUs seem to have quite a power buffer in capacitors to survive that long... with 300k IOPS it should manage to save with a decent margin.
    Even my old Corsair TX manages to survive micro-outages without computer shutting down or crashing. Afaic ATX2.01 PSU is required to endure at least 17ms power outage without losing output power. With 330k IOPS at hand it should be enough to quick save.

    Not that I'd be all out to go and try :-)
  • beginner99 - Wednesday, October 19, 2016 - link

    This would be something guys at anandtech could test. It would also probably help to build back the sites reputation and output of interesting articles.

    Create a script that does some file system operations, then pull the plug. Repeat 10 times for each drive, driver and settings and see what happens. Yeah a lot of work.
  • leexgx - Tuesday, October 25, 2016 - link

    only intel SSDs that have super caps never lose data ,, Intel 320 and S3500 (some site tested it and only intel SSDs never corrupted some SSDs flat out failed the Crucial M4)
    http://lkcl.net/reports/ssd_analysis.html
    http://www.extremetech.com/computing/173887-ssd-st...
    normal SSDs that have small caps (not super caps) that say they have power loss protection that is only there to protect the page table from bee trashed not the data it self that is currently been written that still be loss
  • Gigaplex - Tuesday, October 18, 2016 - link

    "then that would imply that most or all of the vendor-specific NVMe drivers are playing fast and loose with data safety"

    I would not be surprised if that's exactly what they're doing.

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