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

Our ADATA XPG SX950 didn't seem to ever make use of the slumber power state; it draws about 0.8W with or without power management enabled. This is a relatively high active idle power draw for a SATA SSD, and the lack of deeper idle is unacceptable for mobile use.

Idle Wake-Up Latency

The bright side of not using any deep idle states is that the ADATA XPG SX950 doesn't take any time to wake up; the 16µs latency we measured is pretty much all on the host side. Phison's SATA drives also do very well on this metric, and the rest all need more than half a millisecond to wake up.

Mixed Read/Write Performance Conclusion
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  • menthol1979 - Monday, October 9, 2017 - link

    Oh dear God, another SSD that has absolutely no reason of existence. Really bored to see another SSD that gets pwned by 850 EVO (leave the PRO). I wonder if manufacturers actually test and benchmark their products before driving them to market.
  • Stochastic - Monday, October 9, 2017 - link

    Agreed.
  • ddriver - Monday, October 9, 2017 - link

    Sadly, very little of what humans do is because it is necessary or it makes sense.
  • Reflex - Monday, October 9, 2017 - link

    @ddriver And yet you continue posting...
  • Samus - Monday, October 9, 2017 - link

    lolz
  • ddriver - Monday, October 9, 2017 - link

    Moot point, as I don't identify with the human herd. Cattle mentality and the accompanying irrational behavioral patterns don't sit well with me. Which is also why I refer to humans in third person, a subtle nuance an intelligent person would have read into.

    But not you though, you perfectly fit the profile, seeing how once again you fail at getting stuff or making sense ;) But still, an understandable effort, you are probably still hurting by that chain of pwnage. And it's only parroting cliches because you really cannot do better.

    You humans, sometimes I am amazed you made it this far. And since you wouldn't get the nuance, there are two contexts to that, the first being that you still haven't succumb to your stupidity, and the second being "this far into devolution". I suppose that's why you cherish the establishment and its mediocrity so much, even if it is what pushes you to regress into cattle, you still get to survive, suckling at its toxic tit. It's your mommy, that's what your infant mind can identify it as, not as what it really is.
  • ddriver - Monday, October 9, 2017 - link

    And just in case you are perplexed how me responding to your post is something that makes sense, since you obviously can't get all this, it is quite simple - you are not the intended audience, just the means of making a point for the occasional few that can get it ;)
  • vgray35@hotmail.com - Tuesday, October 10, 2017 - link

    This quote "Sadly, very little of what humans do is because it is necessary or it makes sense," is a telling feature reveal of this AI Cyborg miscreant, who apparently has a deep rooted need for focusing on humans, describing humans, engaging humans, belittling humans; and it's apparent its existence and glorified self aggrandizement is defined solely on the existence lowly humans, as evidenced by the closing statement "you are not the intended audience ...".

    Sadly, very little of what this AI cyborg does makes sense. Prattle over product reviews is merely pretense of know how . Sadly no one has yet found the power down switch for this AI cyborg. For as much as it exudes disdain for humans, yet its very reason for being relies entirely on the necessity for engaging with them, to establish meaning in its miserable existence. These posts are its food, and a belittlement posture its means of self aggrandizement compensating for its low class software programming. The prattle is evidence that surely this really is no human (as it itself claims). It needs a firmware upgrade and an implant to put it out of its misery. I wish scientists would stop creating such experimental specimens for their own misguided research.
  • mapesdhs - Wednesday, October 11, 2017 - link

    vgray, that was awesome. 8)
  • svan1971 - Wednesday, October 11, 2017 - link

    Bravo !

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