The Crucial P1 1TB SSD Review: The Other Consumer QLC SSD
by Billy Tallis on November 8, 2018 9:00 AM ESTConclusion
The Crucial P1 SSD doesn't leave us particularly excited about the near-term prospects for QLC NAND in the consumer SSD market. The P1 is a decent entry-level NVMe SSD for less intensive workloads, but the wide gap between its best and its worst performance means the P1 comes with more caveats than most of its competition.
The Crucial P1 relies very heavily on its SLC cache to provide high performance, and that cache shrinks as the drive fills up. When the drive is full, a very write-heavy workload can overflow the cache and severely impact write speeds and even read performance to some extent. However when the drive isn't close to full, it is nearly impossible to fill the SLC cache with a realistic workload, and the Crucial P1 performs at least as well as any other entry-level NVMe drive, and sometimes rivals high-end NVMe drives. Compared to the Intel 660p, the SLC cache on the Crucial P1 seems to be more write-oriented and is not as good at accelerating read operations. It seems like the P1 may be a bit quicker to evict data from the cache and compact it into QLC blocks.
Overall the Crucial P1 is primarily aimed at consumer machines, and that definitely seems like the segment it's best suited for. A typical consumer use case would involve most of the large data on the drive coming from things like movies and video games that are rarely modified, as opposed to workstation workloads that generate massive files that constantly change. This is helpful to the P1 because it reduces the actual amount of writing the drive needs to do, though it does mean that the drive's variable-size SLC cache could end up quite small. On balance, even that small cache should be adequate given the limited amount of data that does change with most consumer workloads; though to be sure, overflowing the SLC cache is something that would be far more noticeable on the P1 than most TLC-based SSDs. But it is still not something that will happen to most consumers often enough to worry about.
That leaves the Crucial P1 as usually being very fast, and definitely faster overall than any SATA SSD. The use of QLC NAND doesn't cripple the drive, and is a detail that most consumers don't have to care about. Even at its worst, the P1 is still faster and more efficient than a mechanical hard drive. NVMe SSDs should aspire to more than that, but this will probably be true even of QLC SATA drives as long as they also avoid the low capacity points where high performance is impossible.
| NVMe SSD Price Comparison | ||||
| 240-280GB | 480-512GB | 960GB-1TB | 2TB | |
| Crucial P1 | $109.99 (22¢/GB) | $219.99 (22¢/GB) | Coming Soon | |
| Intel 660p | $99.99 (20¢/GB) | $189.99 (19¢/GB) | $349.99 (17¢/GB) | |
| MyDigitalSSD SBX | $54.99 (21¢/GB) | $94.99 (19¢/GB) | $219.99 (21¢/GB) | |
| Kingston A1000 | $56.99 (24¢/GB) | $97.99 (20¢/GB) | $219.99 (23¢/GB) | |
| MyDigitalSSD BPX Pro | $74.99 (31¢/GB) | $129.99 (27¢/GB) | $259.99 (27¢/GB) | $519.99 (27¢/GB) |
| ADATA XPG SX8200 | $62.99 (26¢/GB) | $107.99 (22¢/GB) | $214.99 (22¢/GB) | |
| HP EX920 | $73.99 (29¢/GB) | $119.99 (23¢/GB) | $199.99 (20¢/GB) | |
| WD Black (2018) | $85.99 (34¢/GB) | $138.46 (28¢/GB) | $259.75 (26¢/GB) | |
| Samsung 970 EVO | $87.90 (35¢/GB) | $147.99 (30¢/GB) | $227.99 (23¢/GB) | $577.95 (29¢/GB) |
| SATA Drives: | ||||
| Crucial MX500 | $52.99 (21¢/GB) | $84.95 (17¢/GB) | $154.99 (15¢/GB) | $328.99 (16¢/GB) |
| Samsung 860 EVO | $57.99 (23¢/GB) | $82.99 (17¢/GB) | $162.99 (16¢/GB) | $347.99 (17¢/GB) |
The downsides of QLC NAND are pretty easy to accept if they come with a significant price cut, but that is not yet the case for the Crucial P1 or the Intel SSD 660p. The Crucial P1 is 22 cents per GB and the Intel 660p is 19 cents per GB, so Micron obviously needs to drop their prices at least a little bit to be at all competitive. Meanwhile, mainstream SATA SSDs are about 16–17 cents per GB for 512GB and larger capacities, and there are some high-performance TLC-based NVMe SSDs in the 20-22 cents per GB range.
Ultimately if you are going to pay extra for a NVMe SSD instead of a SATA drive, at current prices there are far more compelling options than the Crucial P1 and Intel 660p. We're accustomed to seeing entry-level NVMe SSDs get undercut by more popular high-performance drives as prices in general trend downward, and the two QLC drives we have so far on the consumer market are continuing that pattern. When QLC comes to the SATA SSD market, prices will need to be at or below 13 cents per GB to avoid repeating this problem.
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DanNeely - Thursday, November 8, 2018 - link
When DDR2 went mainstream they stopped making DDR1 dimms. The dimms you could still find for sale a few years later were old ones where you were paying not just the original cost of making them, but the cost of keeping them in a warehouse for several years before you bought them. Individual ram chips continued to be made for a while longer on legacy processes for embedded use but because the same old mature processes were still being used there was no scope for newer tech allowing cost cutting, and lower volumes meant loss of scale savings meaning that the embedded world also had to pay more until they upgraded to new standards.Oxford Guy - Thursday, November 8, 2018 - link
The point was:"QLC may lead to higher TLC prices, if TLC volume goes down and/or gets positioned as a more premium product as manufacturers try to sell us QLC."
Stopping production leads to a volume drop, eh?
romrunning - Thursday, November 8, 2018 - link
"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."I really wish all NVMe drives kept a higher base performance level. QLC should have died on the vine. I get the technical advances, but I prefer tech advances increase performance, not ones that are worse than their predecessor. The price savings, when it's actually there, isn't worth the trade-offs.
Flunk - Thursday, November 8, 2018 - link
In a year or two there are going to be QLC drives faster than today's TLC drives. it just takes time to develop a new technology.Oxford Guy - Thursday, November 8, 2018 - link
Faster to decay, certainly.As I understand it, it's impossible, due to physics, to make QLC faster than TLC, just as it's impossible to make TLC faster than MLC. Just as it's impossible to make MLC faster than SLC.
Workarounds to mask the deficiencies aren't the same thing. The only benefit to going beyond SLC is density, as I understand it.
Billy Tallis - Thursday, November 8, 2018 - link
Other things being equal, MLC is faster than TLC and so on. But NAND flash memory has been evolving in ways other than changing the number of bits stored per cell. Micron's 64L TLC is faster than their 32L MLC, not just denser and cheaper. I don't think their 96L or 128L QLC will end up being faster than 64L TLC, but I do think it will be faster than their 32L or 16nm planar TLC. (There are some ways in which increased layer count can hurt performance, but in general those effects have been offset by other performance increases.)Oxford Guy - Thursday, November 8, 2018 - link
"Other things being equal, MLC is faster than TLC and so on"So, other than density, there is no benefit to going beyond SLC, correct?
Billy Tallis - Thursday, November 8, 2018 - link
Pretty much. If you can afford to pay for SLC and a controller with enough channels and chip enable lines, then you could have a very nice SSD for a very unreasonable price. When you're constrained to a SATA interface there's no reason not to store at least three bits per cell, and even for enterprise NVMe SSDs there are only a few workloads where the higher performance of SLC is cost-effective.Great_Scott - Monday, November 12, 2018 - link
They should drop the SLC emulation and just sell the drive as an SLC drive. Sure, there may be some performance left on the table due to the limits of the NVME interface, but the longevity would be hugely attractive to some users.They'd make more money too, since they could better justify higher costs that way. In fact, with modern Flash they might be able to get much the same benefit from MLC organization and have roughly half the drive space instead of 25%.
Lolimaster - Friday, November 9, 2018 - link
Do not mix better algorithms of the simulated SLC cache and dram with actual "performance", start crushing their simulated cache and the TLC goes to trash.