One Design, Two Products: The SanDisk Ultra 3D (1TB) and WD Blue 3D (1TB) SSD Reviews, with BiCS 3D NAND
by Billy Tallis on September 14, 2017 9:00 AM ESTPower 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.
Orange is for the new drives, Blue is for the previous generation models
Not much has changed with the power management situation for the WD and SanDisk drives; they're still using the same Marvell 88SS1074 controller, and the choice of NAND doesn't have much effect on idle power. Both active idle and slumber state idle power draw are good.
The idle wake-up latency of the WD/SanDisk drives is plenty quick, but not quite as fast as the Phison-based drives. The drives that most often outperform the WD Blue 3D NAND and SanDisk Ultra 3D all take several times longer to wake up from idle.
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MajGenRelativity - Thursday, September 14, 2017 - link
Looks like a good drive to keep in mind. Congratulations to WD and SanDisk on making a product worthy of challenging the 850 Evo. Good to see the rest of the market FINALLY catching up!nathanddrews - Thursday, September 14, 2017 - link
Knowing that SATA is just about completely tapped at this point, it would just be nice if we could get these drives down to the $0.10/GB range.MajGenRelativity - Thursday, September 14, 2017 - link
Unfortunately, that won't happen while we're in the middle of a NAND shortage/price fixing epidemicDanNeely - Thursday, September 14, 2017 - link
Agreed. I'm hoping that by next year the large scale switch over from planar to 3d nand will be complete and the supply situation will be less squeezed.MajGenRelativity - Thursday, September 14, 2017 - link
Yep. I hope DRAM prices go down tooDanNeely - Thursday, September 14, 2017 - link
Same, although a shortage caused by rising demand is at least a good problem to have after years of the consumer PCs decline dragging the industry down.MajGenRelativity - Thursday, September 14, 2017 - link
That's true, assuming the "shortage" is caused by rising demand. I have no proof either way, so you quite well could be right.melgross - Wednesday, September 20, 2017 - link
Much of it is coming from increasing smartphone and tablet storage. For example, Apple now has either 64GB or 256GB for their phones, and up to 512GB for the Pro tablets. Those are pretty large numbers, and along with some Android models, are sucking a lot of NAND and RAM out of the market.smilingcrow - Thursday, September 14, 2017 - link
The demand is coming from other areas not PCs and that's only half of it.The other is that they have kept supply low so not to get into the same over supply issue that they have had before.
The very low RAM prices were unsustainable due to massive losses but not sure if NAND has ever been sold below cost.
MajGenRelativity - Thursday, September 14, 2017 - link
Ah