Power Management

Real-world client storage workloads leave SSDs idle most of the time, so the active power measurements presented earlier in this review only account for a small part of what determines a drive's suitability for battery-powered use. Especially under light use, the power efficiency of a SSD is determined mostly be how well it can save power when idle.

SATA SSDs are tested with SATA link power management disabled to measure their active idle power draw, and with it enabled for the deeper idle power consumption score and the idle wake-up latency test. Our testbed, like any ordinary desktop system, cannot trigger the deepest DevSleep idle state.

Idle power management for NVMe SSDs is far more complicated than for SATA SSDs. NVMe SSDs can support several different idle power states, and through the Autonomous Power State Transition (APST) feature the operating system can set a drive's policy for when to drop down to a lower power state. There is typically a tradeoff in that lower-power states take longer to enter and wake up from, so the choice about what power states to use may differ for desktop and notebooks.

We report two idle power measurements. Active idle is representative of a typical desktop, where none of the advanced PCIe link or NVMe power saving features are enabled and the drive is immediately ready to process new commands. The idle power consumption metric is measured with PCIe Active State Power Management L1.2 state enabled and NVMe APST enabled.

Active Idle Power Consumption (No LPM)Idle Power Consumption

In addition to load power efficiency improvements, the 860 PRO brings modest improvements to  idle power consumption. Samsung's active idle power consumption was already pretty good, but the 860 PRO provides further savings. The idle power in slumber state is a big improvement for both of the 860 PROs, likely due to the use of LPDDR4.

Idle Wake-Up Latency

The idle wake-up latency of Samsung's drives hasn't changed, and is still hovering just above 1ms.

Mixed Read/Write Performance Conclusion
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  • Flunk - Tuesday, January 23, 2018 - link

    I agree, the low price makes the mx500 a really good buy. It certainly qualifies as "fast enough" while delivering very low cost/GB.
  • GreenMeters - Tuesday, January 23, 2018 - link

    Looking like it. The 850 EVO was on sale over Black Friday for less than the MX500 (at 1 TB size anyway), but outside big discounts like that (and assuming there's no simultaneous discount of the MX500) then it looks like Samsung is about to be irrelevant when it comes to SATA. Disappointing in some ways (have four 850 EVOs in various systems now, two of them picked up at the aforementioned sale, and they've been great) but as long as PCI is becoming more affordable I guess it's not a big deal.
  • Alistair - Tuesday, January 23, 2018 - link

    You are comparing with the launch price of the MX500. I've bought 5 x MX500 1TB drives for $242 USD each. I'm pretty sure the Samsung 850 is more expensive.
  • Samus - Wednesday, January 24, 2018 - link

    If you are going to compare sale prices of Samsung drives to the competition, it becomes even more obvious Samsung is a bad buy when you see the sale prices of competitors. The BX300 256GB drives were on sale for $70 at one point. No Samsung 250GB drive has been under $90 in over a year, even on sale.
  • bug77 - Wednesday, January 24, 2018 - link

    SATA does not prevent performance improvements. 4k random reads are what give a drive its speed for home usage and we're not even at 100MB/s in this aspect. Plenty of room for improvement right there.

    In other news, if you have ~$250 to spend, you can either get a 512GB 850 Pro or a 1TB MX500. Imho, as good as Samsung is, there's no contest here.
  • zodiacfml - Sunday, February 11, 2018 - link

    I agree. The only limit is in sequential. However, we have seen the performance/capabilities of the Intel Optane drives and that even that doesn't improve a desktop experience by any noticeable level.
  • Round - Wednesday, January 24, 2018 - link

    Sorry, but I disagree. What's so impressive about this, because I'm not seeing it? They improved the power spec, but for real world use, especially in a desktop, I'm just not seeing any benefit at those prices.

    I can't see buying any more Samsung drives (I have 6 850 Evos) or recommending them to anyone. The price/performance from Crucial is superior, and I doubt anyone is ever going to notice a performance difference between the MX500 and 850/860 Evos (the 860 Pro is priced ridiculously high and is not a wise purchase for any average user).

    I find myself hoping Samsung gets punished in the market place....
  • StrangerGuy - Wednesday, January 24, 2018 - link

    Yup, I fail to see whats so great about this SSD either for consumers either. MX500 beats it in 4K random IOPS while having a much higher GB/$. The extra endurance and warranty length is also completely irrelevant for 99.99% of consumers out there; I myself have a Crucial M550 1TB since 2014 and I still only have 11TB total writes on it.
  • BurntMyBacon - Wednesday, January 24, 2018 - link

    While I don't find this drive particularly impressive (not much room to impress on SATA anymore), it does have the distinction of likely being the last MLC drive available on SATA. While normal consumers can (in theory) use TLC drive with no negative effect, there are cases of people who have experienced a TLC SSD failure and aren't too eager to get another. I've personally been involved with 7 TLC SSD failures (3 different Crucial models, 2 Sandisks, and 2 Samsung). While the NAND was not likely responsible for any of these failures and this makes up a pretty low percentage of total TLC SSDs deployed within my purview, it does start to leave a less reliable image when compared to the zero MLC SSD failures (Crucial, Intel, Samsung, Sandisk, Corsair, etc.) I've seen in my client base. Granted, this is all anecdotal and I use global data (including HDD vs SSD failure rates) to color my recommendations. However, clients who've experienced the drive failures have universally decided that TLC was not an option for them. I haven't sworn off TLC drives personally, but entirely coincidentally, I have yet to purchase one since I burnt one out under heavy load (improper cooling on the controller I believe).
  • chrone - Tuesday, January 23, 2018 - link

    Could you guys perform synchronous write test in Linux as well?

    ```
    dd if=/dev/zero of=/tmp/test bs=4K count=100 oflag=direct,sync status=progress
    dd if=/dev/zero of=/tmp/test bs=4M count=100 oflag=direct,sync status=progress
    ```

    Sadly, the synchronous write for older Samsung SSD 850 Pro is similar to HDD. Synchronous write are used by OS and app for data consistency and reliability in Linux environment.

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