Performance Consistency

Kicking things off, our performance consistency test saturates the drive with 4kB random writes for a full hour, with a queue depth of 32, the maximum supported by the AHCI protocol used by SATA and most PCIe drives. This puts the drive's controller under maximum stress and writes enough data to exhaust all free space and spare area on the drive. This is an unrealistic workload for any client use, but it provides a worst-case scenario for long-term heavy use, and it sheds light on how different SSD controllers behave and if their performance will hold up as they fill up.

The average of the last 400 seconds of the test gives us a steady-state IOPS rating that is usually very different from what the manufacturer specifies for a new, empty drive. We also quantify the consistency of the drive's random write performance, and provide plots of the performance over the course of the test.

Steady-State 4KB Random Write Performance

Once steady state is reached, performance is determined more by the controller's algorithms than the interface speed, so it's not too surprising to see the 950 Pro performing similarly to other Samsung drives.

Steady-State 4KB Random Write Consistency

The consistency metric shows a surprising disparity between the two 950 Pros, with the 256GB performing much better.

Samsung 950 Pro 256GB
Default
25% Over-Provisioning

Comparing the graphs of the two 950s shows that the inconsistency of the 512GB drive comes from frequent jumps in performance above a solid baseline. This pattern holds even for the test with overprovisioning. Graphing the power consumption over time (not shown) reveals that the periods of lower performance have lower power. If the lower performance were due to periodic background garbage collection, then we would expect power consumption to be at least as high as when the drive is performing well. Instead, it appears that the 512GB drive is experiencing thermal throttling.

Samsung 950 Pro 256GB
Default
25% Over-Provisioning

With most of its time spent thermally limited, our 512GB sample's low average is explained. It appears that the thermal throttling mechanism is bumping the drive down to one of several discrete performance levels, rather than a continuous performance mechanism.

Testing With NVMe Over PCIe AnandTech Storage Bench - The Destroyer
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  • SunnyNW - Saturday, October 24, 2015 - link

    Actually shame on you for telling others what their priorities should be. Boot times are Very important to me and was one of the main reasons I upgraded from a hdd to a ssd in the first place. I dont want to have to wait more than the 15 seconds it takes my system to boot right now. People have to boot/restart their machine for various reasons and variable amounts of times, I dont want to have to wait more than 20 sec or so Every time I update software/drivers that require a reboot (windows update, gpu driver update, etc.). Almost every time I leave my house for more than 8 hrs or so I shut down my machine, I just dont have good luck with sleep on it, not sure if it's because of the radeon or what but ehh.
  • Rajinder Gill - Saturday, October 24, 2015 - link

    If you leave the house for 8 hours, your time cannot be worth enough money to be worried about 20 seconds of BOOT time :)
  • SunnyNW - Sunday, October 25, 2015 - link

    LOL!!! You are one Hilarious (my most polite way of saying pathetic) character. If you had any clue as to how much I Actually earn for my time, from all my various ventures especially my business, your ugly little smiles at the end of all your comments would more accurately be portrayed with a symbol that expressed your jaw wide open and hitting the floor. : 0 And how many times are you going to mention S3, lol, let me guess it's something you just recently learned about so you spout off about it Every single chance you get. Please don't reply to my comments in the future. I come here for intelligent interactions, not some nonsense from someone that has No Clue. Thank You in advance, Oh and just for you ;)
  • Rajinder Gill - Sunday, October 25, 2015 - link

    S3 resume, USE IT! One more time just for you :)
  • xype - Monday, October 26, 2015 - link

    SunnyNW, I never met one single person who made a shitload of money "with their time" who spent that time arguing online on tech sites, and arguing trivialities like SSD boot times—congrats, you’re the first!

    No person I know that makes $150+/hour gives a shit about boot times, and the people who do (working in IT, specifically high availability infrastructure ops) are in a whole different market from the one that AnandTech usually covers.
  • SunnyNW - Monday, October 26, 2015 - link

    You are entitled to your opinion. But I agree, this was the first time I made a reference to my personal life finances thru comments and there is no need for that here. I just become Very annoyed when one judges others' priorities and I was already upset from other bs. Anyway not one of my finer moments.
  • SunnyNW - Monday, October 26, 2015 - link

    Lastly Ill add that 'making wrong assumptions' (especially when insulting) and 'questioning others priorities' are my pet peeves. On any other site I would not have replied in the first place. I dont know why but I feel differently when it comes to anandtechs community, I feel there is a higher standard here and many of the comments are usually very informative and worthwhile discussions. I work extremely hard and do not need someone telling me how much my time is worth. I hate when people sit behind their computer making assumptions about someone that they know absolutely nothing of, I do not expect that from the community here. I highly respect most of the commenters on anandtech and would like that in return. I feel anandtech is full of mostly intellectual persons. There are not many commenters on anandtech like mr. gill and I just let him get to me way more than I should have. Again I shouldnt have to explain myself to you but iunno here I am doing just that...I just turned 22 recently so gimme a beak, I'm learning.
  • Rajinder Gill - Saturday, October 24, 2015 - link

    If the sleep issues are due to the Radeon and BOOT time is that important, then perhaps a S3 resume complaint VGA would get you back to the desktop quicker. ;)
  • SunnyNW - Sunday, October 25, 2015 - link

    What is a "S3 resume complaint?" I have no complaints with my GPU and am very content with the 15 seconds it takes my machines to reach the desktop.
  • ewitte - Thursday, November 12, 2015 - link

    Working in IT the most annoying thing is boot times on OTHERS machines. I still run into spinning drives and insufficient memory which could be upwards of 10 minutes before performance stabilizes after a reboot.

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