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

Idle Wake-Up Latency

The Optane SSD 800p has a bit of an unusual suite of power management capabilities. Previous Optane products have not implemented any low-power sleep states, giving them quite high idle power consumption but entirely avoiding the problem of latency waking up from a sleep state. The 800p implements a single low-power sleep state, while most NVMe SSDs that have multiple power states have at least two or three idle states with progressively lower power consumption in exchange for higher latency to enter or leave the sleep state. On the other hand, the 800p has three tiers of active power levels, so devices with strict power or thermal limits can constrain the 800p when properly configured.

Unfortunately, our usual idle power testing method didn't work with the 800p, leading it to show only a modest reduction in power rather than a reduction of multiple orders of magnitude. This may be related to the fact that the Optane SSD 800p indicates that it may take over a full second to enter its idle state. This is an unusually high entry latency, and something in our system configuration is likely preventing the 800p from fully transitioning to idle. We will continue to investigate this issue. However, based on the specifications alone, it looks like the 800p could benefit from an intermediate idle state that can be accessed more quickly.

(I should mention here that the last Intel consumer SSD we reviewed, the 760p, also initially showed poor power management on our test. We were eventually able to track this down to an artifact of our test procedure, and determined that the 760p's power management was unlikely to malfunction during real-world usage. The 760p now ranks as the NVMe SSD with the lowest idle power we've measured.)

Mixed Read/Write Performance Conclusion
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  • Alexvrb - Saturday, March 10, 2018 - link

    Calin you are obviously too young to remember some of the early "affordable" consumer NAND SSDs. Hammer them a bit and they stalled... producing worse results than a lot of fast HDDs... especially in random writes. Sequential speeds were never a major issue that I can recall. Reply
  • The_Assimilator - Friday, March 9, 2018 - link

    Trying to equate a NAND-to-Optane transition to the mechanical-HDD-to-SSD transition is laughable. Reply
  • wumpus - Friday, March 9, 2018 - link

    The moment pseudo-SLC in TLC showed up, Optane was pretty much dead in the SSD market. They would presumably compete with SLC (does anybody still make it?), but TLC is the coffin nail in consumer markets.

    From the moment the 3d-xpoint hypetrane started, it was clear that it would try to wedge itself into the memory hierarchy, presumably between flash and DRAM, and hopes for replacing flash.

    Flash isn't going anywhere, and 3d-xpoint hasn't shown the endurance needed for a fast-paging DRAM replacement. It certainly wouldn't replace *all* DRAM, but anyone who's seen a 4GB machine actually function (slow, but they do work) knows that nearly all that expensive (hopefully DDR4 will fall back to Earth) DRAM could be replaced by something sufficiently fast, but neither flash nor 3d-xpoint is quite there.

    To compound the problems, Intel decided that "Optane in a DDR4 slot" would be strictly proprietary. So there are marketing/political problems trying to get manufacturers to support it as well as technical issues to make the stuff.
    Reply
  • name99 - Friday, March 9, 2018 - link

    Consumer NAND launched in an environment where it had SOME spaces where it was optimal, and so had the chance to grow. It started in phones and DAPs, then grew to ultra-laptops, and finally the desktop. Point is --- there were niches that could pay for on-going improvement.

    Octane is different because there is NO obvious niche that justifies continuing to pump money into it. The niche that was SUPPOSED to justify it (NV-DIMMs) is STILL MIA years after it was promised...
    Reply
  • iwod - Friday, March 9, 2018 - link

    I am all for super fast QD1 results. But so far none of the application seems to benefits from it. At least not according to test results. I am wonder, we are either testing it wrong, looking at the wrong thing, or the benefits of QD1 is over thought and bottleneck is somewhere else.

    And NAND continues to get bigger better and faster. We may be looking at below $100 250GB SSD this year.
    Reply
  • iter - Friday, March 9, 2018 - link

    Exactly. It is hilarious how them fanboys keep claiming that we overlook the advantages, when I explicitly state them almost every time.

    There are very little and far in between workloads where those advantages can translate into tangible improvement of real world performance.

    When your bottleneck is a human being interacting via input devices, discrete savings of several dozens of microseconds are simply not perceivable.

    Even cumulative savings are in fact not, because most of the time that data has to also be processed by the cpu, which is why synthetics aside, raw real world applications snow minuscule going from a decent ssd to a crazy fast nvme device.
    Reply
  • sor - Friday, March 9, 2018 - link

    Probably has something to do with your name calling and “it keeps getting worse and worse” when that objectively isn’t true. You come off as having an axe to grind.

    It is not true that this is worse and worse. The power improvements shown here are quite impressive. Low QD performance is still better than NAND by an order of magnitude, and looks to have gotten a roughly 20% improvement. Sequential read now even beats NAND.

    You and others are falling over yourselves to crap on it for some strange reason, and clearly are ignoring the upsides. It’s just a product.
    Reply
  • iter - Friday, March 9, 2018 - link

    "when that objectively isn’t true"

    It absolutely is. It is slower than the 900p. They improved power a bit - big whoop, especially considering it came at the cost of gutting the interface by 50%.

    118 GB? I bet enthusiasts all over the planet are drooling about that crazy capacity. Not to mention the smaller model...

    Nobody denies the strong points, it is just that they are way too little to make this a good product.

    Instead of getting bigger and faster it gets smaller and slower.

    And somehow the price per GB increases.

    Truly impressive.
    Reply
  • nevcairiel - Friday, March 9, 2018 - link

    If you want to go down that road, at current consumer SSD speeds (say Samsung 960 Pro), I doubt any normal user would even notice if the performance suddenly doubled (or halfed, for that matter).

    Does that mean we should not innovate? Perhaps consumer work-load isn't the main goal, but if you have the hardware, why not try to make a consumer product, anyway.
    Reply
  • MrSpadge - Friday, March 9, 2018 - link

    With decently fast SATA SSDs the bottleneck is almsot entirely the CPU already, unless you've got purely I/O load. Reply

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