The Crucial P1 SSD isn't quite the first at anything, but it is still a very novel product. It is the second consumer SSD on the market to use four bit per cell (QLC) NAND flash memory, after the Intel SSD 660p. It's the second QLC SSD from Micron, after their 5210 ION enterprise SATA SSD that started shipping to select partners in May (and is now starting to be more widely available).

More importantly however, it is the first consumer NVMe SSD that Micron has actually shipped. For all of their storied history in the SSD industry, Micron is pretty much the last SSD maker to enter the consumer NVMe market; and not for a lack of trying. The company's first attempt at an NVMe drive, the 2016 Ballistix TX3, was ready to hit the market but was canceled when it became clear that it would not have been competitive. So this drive is a very important one for the company, despite the fact that its use of an NVMe/PCIe interface is hardly the most interesting aspect of the Crucial P1.

Under the hood, the Crucial P1 starts from the same basic ingredients as the Intel 660p: Intel/Micron 64-layer 3D QLC NAND and the Silicon Motion SM2263 controller. Micron has added their own firmware customization atop Silicon Motion's work, and the design of the Crucial P1 differs from the Intel 660p in several aspects — so this is not a case of two brands selling the exact same reference design SSD.

Where the Intel 660p includes just 256MB of DRAM regardless of drive capacity, the Crucial P1 includes the same 1GB DRAM per 1TB NAND ratio that is used by most mainstream SSDs. This extra DRAM on the Crucial P1 should enable marginal improvements on benchmarks and workloads that touch large amounts of data, and probably allows a slight simplification to the drive's firmware. The Crucial P1 also has slightly lower usable capacities, eg. 500GB instead of 512GB, so there's a bit more spare area for the controller to work with. And whereas Intel's 2TB 660p is still a single-sided M.2 module, the upcoming 2TB Crucial P1 will have NAND and DRAM on both sides.

The rest of the architecture of the Crucial P1 follows the same general strategies as the Intel 660p. The SM2263 controller is the smaller four-channel design from Silicon Motion's current generation, though it is a step above the DRAMless SM2263XT variant. The host interface is a PCIe 3.0 x4 link, but the Crucial P1 barely needs more than the PCIe 3.0 x2 link used by some competing entry-level NVMe controllers: peak sequential transfers for the P1 are only about 2GB/s.

Crucial P1 SSD Specifications
Capacity 500 GB 1 TB 2 TB
Form Factor Single-sided M.2 2280 Double-sided M.2 2280
Interface NVMe 1.3 PCIe 3.0 x4
Controller Silicon Motion SM2263
NAND Flash Micron 64L 3D QLC NAND
DRAM 512MB DDR3 1GB DDR3 2GB DDR4
Sequential Read 1900 MB/s 2000 MB/s 2000 MB/s
Sequential Write 950 MB/s 1700 MB/s 1750 MB/s
Random Read 90k IOPS 170k IOPS 250k IOPS
Random Write 220k IOPS 240k IOPS 250k IOPS
SLC Write Cache (approximate) 5GB min
50GB max
12GB min
100GB max
24GB min
200GB max
Power Max 8W
Idle 2mW (PS4), 80mW (PS3)
Warranty 5 years
Write Endurance 100 TB
0.1 DWPD
200 TB
0.1 DWPD
400 TB
0.1 DWPD
MSRP $109.99 (22¢/GB) $219.99 (22¢/GB) TBA

The use of QLC NAND means that the Crucial P1 is highly reliant on its SLC write cache to enable performance that can exceed what SATA SSDs provide. This is because the drive's QLC NAND isn't all that high performing on its own; it's dense, but it takes longer to program a block than MLC or TLC NAND. TLC for that matter is cache-sensitive for similar reasons, but QLC in turn has cranked up the importance of cache sizes and caching algorithms another notch, as the performance delta between the cache and the actual storage has increased.

For Crucial's P1 the SLC cache is variable in size, and on a nearly-empty drive the cache will be substantially larger than what is usually found on TLC SSDs. Consumer drives that use TLC NAND often try to limit the maximum size of their SLC caches in order to reduce the amount of background work necessary in the event that the SLC write cache should overflow. The Crucial P1 is designed to do as much as possible to avoid falling off that performance cliff, rather than attempt to mitigate the effects when it does happen.

When the SLC cache fills up, writes to the P1 get very slow. The P1 doesn't bypass the cache when it is full, so everything written to the drive is written to SLC first before being folded into QLC blocks. (This helps the P1 offer similar partial power loss protection to the Crucial MX series of SATA SSDs.) The P1 also tends to keep data in SLC so it can serve as a read cache instead of aggressively folding data into QLC blocks during idle time.

All told, the caching strategy of the Crucial P1 maximizes performance and endurance for typical lightweight consumer/client storage workloads, but at the cost of performance on storage-intensive workloads. The P1 is definitely not the SSD to use in a workstation that regularly reads and writes datasets of many gigabytes, but it should be fine for more common desktop usage that is fairly read-heavy and only does multiple GB of writes on rare occasions such as when installing large software packages. This is in some sense just an amplification of the trends we saw as the SSD market moved from MLC to TLC NAND, but we do now have high-end TLC drives that can maintain high write speeds even after their SLC caches have filled. This is not true of the current two consumer QLC SSDs, and will probably always be a significant weakness of QLC SSDs.

The other major tradeoff to the Crucial P1's use of QLC NAND is the lower write endurance compared to TLC SSDs. The P1 is rated for about 0.1 drive writes per day under a five-year warranty, while most consumer SSDs are rated for 0.3 up to about 1.0 DWPD for either three or five years. The P1 somewhat mitigates this by only offering large capacities of 500GB and up, so the total write endurance starts at a minimum of 100TB. This is adequate provided that most of the drive's capacity is used for static data. If the P1 has to hold hundreds of GB of data that changes as frequently as a web browser's cache and history, then 0.1 DWPD won't be enough. But in a more normal scenario where most of the data is media like movies and video games, then there's no problem.

The early projections for QLC NAND write endurance were in the ballpark of a few hundred program/erase cycles at most, which would have required the QLC SSDs to be treated very carefully. The QLC NAND that Micron is now producing in volume can last for a similar number of P/E cycles as early TLC NAND, which is how the Crucial P1 can be usable for general-purpose consumer storage duties. Even after accounting for the write amplification caused by SLC caching and a realistic proportion of writes being random, the P1 is still rated for the equivalent of 200 full drive writes on the host side. (If those drive writes were entirely large-block sequential writes such as from re-imaging an entire drive, then the P1 should last much longer, but Micron doesn't want to complicate the endurance specs for their consumer drives that much.)

In spite of the tradeoffs of lower performance and endurance, QLC drives like the Crucial P1 are worth a look because of their potential to also have significantly lower prices. At around 22¢/GB currently, the P1 isn't setting any records yet. Several industry reports have indicated that yields of Intel/Micron QLC are still poor, so the production costs of SSD-quality QLC aren't meaningfully lower than TLC yet. The other major NAND manufacturers are being less aggressive about bringing QLC to market, but once they have introduced their competitors we will probably see QLC products offering a more significant discount over TLC. NAND prices in general are also in decline, with some higher-volume TLC products leading the way ahead of even the QLC drives.

The primary competition for the Crucial P1 is its close relative Intel 660p, as well as other entry-level NVMe SSDs. There is a low-end NVMe market segment with numerous options, but they are all struggling under the pressure from more competitively priced high-end NVMe SSDs. Products like the DRAMless Toshiba RC100 and HP EX900 haven't been able to get any traction when the HP EX920 is hitting the same prices. Thus, it is also fair to compare the Crucial P1 against such faster NVMe drives. The P1 is a modest step up in price over mainstream SATA SSDs, so this review includes benchmark results from the Crucial MX500.

AnandTech 2018 Consumer SSD Testbed
CPU Intel Xeon E3 1240 v5
Motherboard ASRock Fatal1ty E3V5 Performance Gaming/OC
Chipset Intel C232
Memory 4x 8GB G.SKILL Ripjaws DDR4-2400 CL15
Graphics AMD Radeon HD 5450, 1920x1200@60Hz
Software Windows 10 x64, version 1709
Linux kernel version 4.14, fio version 3.6
Spectre/Meltdown microcode and OS patches current as of May 2018
AnandTech Storage Bench - The Destroyer
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  • Lolimaster - Friday, November 9, 2018 - link

    With worse of everything how is it going to be "faster", do any TLC SSD beat the Samsung MLC ones? No. Reply
  • npz - Friday, November 9, 2018 - link

    The ONLY reason why TLC is fast today is because of 3D VNAND combined with caching. People are comparing 3D TLC with planar MLC. If you want and apples-to-apples comparison, you'll see that 3D MLC is still more performant and more durable than 3D TLC.

    All of the performance of QLC will come from the pseudo SLC cache, yet that doesn't help with durability nor in situations where you overflow it, or where it's not desirable (which is why Micron doesn't use one on their server focused QLC -- see how pitiful it is then).

    What salvaged TLC was the transition to larger process 3D NAND. Small process planar TLC was not good. Now what will salvage QLC?
    Reply
  • FunBunny2 - Friday, November 9, 2018 - link

    "Now what will salvage QLC?"

    unfortunately, too many humans believe that people 'invent' things. people don't. all they do, at best, is figure out how Mother Nature actually works. you can't fool Mother Nature. and you sure can't make up physics that happens to fit your deepest desires, and yet defies good ole Mother Nature.
    Reply
  • Valantar - Thursday, November 8, 2018 - link

    What's the point of increasing performance when current top-level performance is already so high as to be nigh unnoticeable? The real-world difference between a good mid-range NVMe drive and a high end one are barely measurable in actual real-world workloads, let alone noticeable. Sure, improving random perf would be worthwhile, but that's not happening with flash any time soon. Increasing capacity per dollar while maintaining satisfactory performance is clearly a worthy goal. The only issue is that this, as with most drives at launch, is overpriced. It'll come down, though. Reply
  • JoeyJoJo123 - Thursday, November 8, 2018 - link

    ^ This.

    For typical end users, even NVMe over SATA3 SSDs don't provide a noticeable difference in overall system performance. Moving to an SSD over an HDD for your OS install was a different story and a noticeable upgrade, but that kind of noticeable upgrade just isn't going to happen anymore.

    Typical end users aren't writing/reading so much off the drive that QLC presents a noticeable downgrade over TLC, or even MLC storage. Yes, right now QLC isn't cheap enough compared to existing TLC products, but we've already done this dance when TLC first arrived on the scene and people were stalwart about sticking to MLC drives only. Today? We got high-end NVMe TLC drives with better read/write and random IOPS performance compared to the best MLC SATA3 drives back when MLC was the superior technology.

    Yeah, it's going to take time for QLC to come down in price, the tech is newer and yields are lower, and companies are trying to fine tune the characteristics of their product stacks to make them both appealing in price and performance. Give it some time.
    Reply
  • romrunning - Thursday, November 8, 2018 - link

    Sure, we lost endurance and speed with the switch from MLC to TLC. But the change from TLC to QLC is much worse in terms of latency, endurance, and just overall performance. Frankly, the sad part is that the drive needs the pseudo-SLC area to just barely meet the lowered expectations for QLC. Some of those QLC drives barely beat good SATA drives.

    We now have a new tech (3D Xpoint/Optane) that is demonstrably better for latency, consistency, endurance, and performance. I'd rather Micron continue to put the $ into it to get higher yields for both increased density/capacity & lower costs. That's what I want on the NVMe side, not another race to the bottom.
    Reply
  • JoeyJoJo123 - Thursday, November 8, 2018 - link

    Sorry, you're not the end consumer that dictates how products get taped out, and honestly, if you were in charge of product management, you'd run the company into the ground focusing on making only premium priced storage drives in a market that's saturated with performance drives.

    The bulk of all SSD sales are for lower cost lower storage options. There is no "race to the bottom", it's just some jank you made up in your head to justify why companies are focusing on making products for the common man. Being able to move from an affordable 500GB SSD on TLC to an similarly priced 1TB SSD in a few years is a GOOD THING.

    If you want preemium(tm) quality products, SSDs with only the HIGHEST of endurance ratings for the massive Read/Write workloads you perform on your personal desktop on a day-to-day basis, SSDs with only the LOWEST of latencies so that you can load into Forknight(tm) faster than the other childerm, then how about you go buy enterprise storage products instead of whining in the comments section of a free news article. The products you want with the technology you need are out there. They're expensive because it's a niche market catered towards enterprise workloads where they can justify the buckets of money.

    You keep whining, I'll keep enjoying the larger storage capacities at cheaper prices so that I can eventually migrate my Home NAS to a completely solid state solution. Right now, getting even a cheap 1TB SSD for caching is super-slick.
    Reply
  • romrunning - Friday, November 9, 2018 - link

    "...how about you go buy enterprise storage products instead of whining in the comments section of a free news article."

    You are taking this way too personally.

    I'm actually thinking more about the business side. I want 3D-Xpoint/Optane to get cheaper & get more capacity so that I can justify it for more than just some specific servers/use-cases. So I'd like Micron to focus more on developing that side than chasing the price train with QLC, which is inferior to what preceded it. With Micron buying out Intel's stake in IMFT for 3D-Xpoint, I just hope the product line diversification doesn't lessen the work to make 3D-Xpoint cheaper & even greater capacities.
    Reply
  • JoeyJoJo123 - Friday, November 9, 2018 - link

    >You are taking this way too personally.

    Talk about projecting. Micron is taping out dozens of products across different product segments for all kinds of users. They're working on 3D-Xpoint and QLC stuff simultaneously and independently from each other. What's happening here is that Micron is producing QLC NAND for this Crucial M.2 SSD, and you're here taking it personally (and therefore whining in a free news article comments section) that Micron isn't focusing enough on 3D-Xpoint and that supposedly their QLC is bad for some reason. Thing is, this news article isn't for you. This technology isn't for you. You decided your tech needs are above what this product is aimed for: affordable, large volume SSDs for lower prices.

    Seriously, calm down. This wasn't an assault orchestrated by Micron against people that need/want higher performance storage options. More 3D-Xpoint stuff will come your way if that's the technology you're looking forward to. Again back to my main point, it's going to take some time for these newer technologies to roll out. Until then, don't whine in comments sections that X isn't the Y you were waiting for. If the article is about technology X, make a half-decent effort keep to the topic about technology X.
    Reply
  • mathew7 - Tuesday, November 13, 2018 - link

    "I'll keep enjoying the larger storage capacities at cheaper prices so that I can eventually migrate my Home NAS to a completely solid state solution."
    Wwwwwhhhhhhhaaaaaaaaaaattttt?? NEVER. You don't understand the SSD limits. I would not do that with SLC (assuming current quality at QLC price).
    Enterprises with SSD NASes only use them for short-term performance storage with hourly/daily backup. Anyone who uses them differently is asking for a disaster.
    Look for linuxconf Intel SSD. There is a presentation where they explain how reading a cell damages nearby cells and manufacturers need to monitor this a relocate the data that is only read.
    I have 2 servers with only 1 SSD each for OS and 8-10TB HDDs for my actual long-term data.
    All my desktops/laptops have SSDs (Intel 320, Samsung 830-860 evo+pro, Crucial BX100/MX300 etc). But anything important on SSDs will be backed-up to HDDs.
    Reply

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