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Crucial P2 SSD Review: Beating SATA Dollar for Dollar

Crucial’s low-cost P2 delivers SATA-breaking speed, even without DRAM

Crucial P2 M.2 NVMe SSD
(Image: © Tom's Hardware)

Update 8/16/21 5:30am PT: Crucial has swapped out the TLC flash that powered the initial P2 SSD we tested with QLC flash, severely reducing performance. We've written an investigation into that matter, which you can read here, with our results showing that the 'new' drives are nearly four times slower at transferring files than the original, read speeds are half as fast in real-world tests, and sustained write speeds have dropped to USB 2.0-like levels of a mere 40 MBps. That’s slower than most hard drives. Unfortunately Crucial made the change without altering the product name or number or issuing an announcement. Crucial claims that the P2 will live up to its specs because the company baked the performance of QLC flash right into the spec sheet at launch. But those specs don’t match the performance you’ll see in numerous reviews of the originally-shipping drives.

As such, we do not recommend purchasing this drive. In this article, we have also inserted additional albums in each test category to reflect the real performance you'll get when purchasing this drive today.

Original Article:

In some ways the Crucial P2 is a step in the right direction, yet in others, it’s a step back. The P2’s single-sided form factor can slide into almost any ultra-thin M.2 NVMe device, and it sips very little power, earning our praise for its efficiency. With a long five-year warranty and NVMe performance, it scores an easy win over any of the SATA SSDs, too. If you’re looking for a cheap boot drive, Crucial’s P2 just may fit the bill depending on the price you catch it at. However, there are telltale signs that the P2 will likely see some hardware changes in its future, with QLC flash likely replacing the TLC we reviewed it with today. That means you could get slower performance with newer revisions of this drive. 

(Image credit: Tom's Hardware)

At 500GB, there is very little price variance between some of the fastest and slowest SSDs, making just a few dollars difference much more worth your while than it is at higher capacities like 1TB and 2TB SSDs – especially during sales. Crucial’s 500GB P2 is very affordable at $65, yet it’s a tougher pick if you consider the other NVMe SSDs out there. With low-cost hardware and a lack of onboard DRAM, Crucial’s P2 can’t hang with the faster and closely-priced competitors that have eight-channel NVMe SSD controllers with DRAM support. Samsung’s 970 EVO Plus, Adata’s SX8200 Pro, WD Black SN750, and Seagate’s BarraCuda 510 all tend to offer more performance for just a few dollars more.

If you can’t stretch your budget beyond the P2’s $65 price, the Silicon Power P34A60 gives the P2 a good run for $60 (at the time of publication). It has HMB tech, too, but is faster than the P2 at game loading and trades blows during mixed workloads. We have to give it to the P2, though, while it wasn’t so snappy to fulfill sequential read requests, it did much better than the P34A60 when we hit it hard with SPECworkstation 3’s prosumer workloads. 

The same goes for the P2 against the P1: While Crucial’s P1 delivers snappier performance under light loads with a DRAM-based design and a fairly large dynamic SLC write cache, its 64-Layer QLC NAND flash holds it back during mixed and write-heavy tasks. Crucial’s P2, with its E13T DRAMless NVMe controller and 96L TLC NAND flash, leverages HMB well enough to deliver more consistent sustained performance. And, with the increased endurance rating over the P1, we give the win to the P2 as an overall victor, for now. 

On the entry-level front, the WD Blue SN550 is the P2’s most imminent threat – the SN550 is the best DRAMless SSD we’ve tested yet. While we don’t have a 500GB sample on hand, based on our experience with the SN500, it should beat the P2 easily. At the same price, the WD Blue SN550 is a better value that should be more responsive due to its fast direct-to-TLC write performance, even after its small SLC write cache fills.

Downright ominous performance ratings don’t bode well for the P2’s future. Crucial only rates the P2 for up to 940 MBps write performance at the 500GB capacity, but it can clearly hit over 1.8 GBps. Random performance specifications are also missing from Crucial’s marketing documents. These are telltale signs that this product will likely see some hardware changes in its future, with QLC flash likely replacing the TLC we reviewed it with today. That means you could get slower performance with newer revisions of this drive. 

We have seen this in the past with the Crucial BX500 lineup. Originally, the company launched a 960GB TLC model and later phased it out for 1,000GB and 2,000GB models with QLC. We can’t say that we are too confident of the controller remaining once the shift occurs, either. But if, or better said, when changes occur, we will keep you up to date. 

MORE: Best SSDs

MORE: How We Test HDDs And SSDs

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  • Alvar "Miles" Udell
    The Intel 660p 512GB drive should have been included as well...
    Reply
  • cryoburner
    The performance doesn't look particularly good, generally being at the bottom of the barrel among the NVMe drives, and even seeing a 23% longer load time than the SATA-based MX500 at the Final Fantasy test. If it's 23% slower than a SATA drive at actually loading things, and 30% slower than the previous P1 model, then what's the point? Higher sequential transfers in some synthetic benchmarks and file copy tests don't mean much if it's going to perform worse at common real-world operations. I certainly wouldn't say that the drive "beats SATA dollar for dollar" or "delivers SATA-breaking speed, even without DRAM" based on those results.

    The indications that QLC flash may be replacing the drive's TLC in a future revision also means the P2 might perform substantially worse than the results shown here, so I hope to see some follow up testing if that ends up being the case. The review says the BX500 did that, and mentions "keeping us up to date" about it, but if I search for BX500 reviews, including the one from Tom's Hardware, they all appear to describe the drive as using TLC and performing better than the drive's specifications would indicate, and no update appears to have been made about the switch to QLC. Sending out faster TLC drives for review, then releasing versions with QLC under the same product name at a later date seems rather shifty.

    Under light operation, Crucial’s P2 offers a snappy and responsive user experience that will surpass any SATA SSD. It trades blows with Silicon Power’s P34A60 and even keeps up with the Samsung 970 EVO Plus, yet gets beat in both the Quick and Full System benchmarks by both of the drives. Crucial’s P1, with its DRAM-based architecture, outperforms both the P2 and P34A60. That proves that DRAM-based designs provide the most responsive user experience, even with slower QLC flash.
    As far as a "responsive user experience" goes, something tells me that these differences of a few millionths of a second are not going to be perceptible. The difference in latency between the fastest and slowest SSD tested here only amounts to around one ten-thousandth of a second, so I don't see how anyone would notice that when it will take a typical monitor around a hundred times as long to update the image to display the output. Maybe a bunch of these operations added together could make some difference, but then more of the drive's performance characteristics will come into play than just latency, so I don't see how that synthetic benchmark would bear much direct relation to the actual real-world experience. It's fine to show those latency benchmark results, but I don't think direct relations to the user experience can really be drawn from them.

    I'd like to see more real-world load time results in these reviews, as that's what these drives will typically be getting used for most of the time. As the Final Fantasy test shows, just because one drive appears multiple times as fast in some synthetic benchmarks or file copy tests, that doesn't necessarily translate to better performance at actually loading things. Practically all of the synthetic benchmarks show the P2 being substantially faster than an MX500 SATA drive, but when it comes to loading a game's files, it ends up being noticeably slower by a few seconds. Is that result a fluke, or are these synthetic tests really that out-of-touch with the drive's real-world performance? These reviews should measure other load times of common applications, games and so on, and not just rely primarily on pre-canned and synthetic benchmarks that seem to be at odds with the one real-world loading test.

    Also, I'd like to see test results for drives that are mostly full. Does the real-world performance tank if the drive is 75% or 90% full, and less space is dedicated to the SLC cache? These benchmark results don't really provide any good indication of that. The graphs showing how much performance drops once the cache is filled are nice, but the size of that cache will typically change as the drive is filled. A mostly-full drive may only have a handful of gigabytes of cache that gets filled even with moderately-sized write operations.

    The P2 lacks DRAM, meaning that it doesn’t have a fast buffer space for the FTL mapping tables. Instead, the P2, like most modern DRAMless NVMe SSDs, uses NVMe’s Host Memory Buffer feature. With it, the SSD can use a few MB of the host system’s memory to provide snappier FTL access, which improves the feeling of ‘snappiness’ when you use the drive.
    A "few MB" is kind of vague. How much system RAM is it actually using? The Crucual P1 had 1GB of DRAM onboard for each 1TB of storage capacity. If the P2 is using 1GB of system RAM for the same purpose, then that's a hidden cost not reflected by the price of the drive itself. This might be especially relevant if one were adding such a drive to a system with just 8GB of RAM. And even on a system with 16GB, that could become more of a concern within a few years as RAM requirements rise for things like games. If one ends up needing to upgrade their RAM sooner due to DRAMless drives consuming a chunk of it, then the cost savings of cutting that out of the drive itself seems questionable, especially given the effects on performance.

    And for that matter, it seems like the performance of system RAM could affect test results more than it does on drives with their own onboard RAM. I'm curious whether running system RAM at a lower speed, or perhaps on a Ryzen system with different memory latency characteristics could affect the standings for these DRAMless drives. The use of system RAM also undoubtedly affects the power test results as well. This drive appears to be among the most efficient models, but is the system RAM seeing higher power draw during file operations in its place?
    Reply
  • seanwebster
    Alvar Miles Udell said:
    The Intel 660p 512GB drive should have been included as well...
    Unfortunately, I don't have one. But, the P1 is very close in performance - so close it is almost a substitute if you want to see how the 660p 512GB may perform.

    cryoburner said:
    The performance doesn't look particularly good, generally being at the bottom of the barrel among the NVMe drives, and even seeing a 23% longer load time than the SATA-based MX500 at the Final Fantasy test. If it's 23% slower than a SATA drive at actually loading things, and 30% slower than the previous P1 model, then what's the point? Higher sequential transfers in some synthetic benchmarks and file copy tests don't mean much if it's going to perform worse at common real-world operations. I certainly wouldn't say that the drive "beats SATA dollar for dollar" or "delivers SATA-breaking speed, even without DRAM" based on those results.

    The indications that QLC flash may be replacing the drive's TLC in a future revision also means the P2 might perform substantially worse than the results shown here, so I hope to see some follow up testing if that ends up being the case. The review says the BX500 did that, and mentions "keeping us up to date" about it, but if I search for BX500 reviews, including the one from Tom's Hardware, they all appear to describe the drive as using TLC and performing better than the drive's specifications would indicate, and no update appears to have been made about the switch to QLC. Sending out faster TLC drives for review, then releasing versions with QLC under the same product name at a later date seems rather shifty.

    Updates I am referring to typically come in news posts or if I am sampled the updated device, it will be reflected in an update in the review. I wasn't aware of the BX500 QLC swap until recently, the week of writing this review, and actually haven't had a moment to notify the team about it until the other day, tho I think I saw a post about it somewhere at one point.

    As far as a "responsive user experience" goes, something tells me that these differences of a few millionths of a second are not going to be perceptible. The difference in latency between the fastest and slowest SSD tested here only amounts to around one ten-thousandth of a second, so I don't see how anyone would notice that when it will take a typical monitor around a hundred times as long to update the image to display the output. Maybe a bunch of these operations added together could make some difference, but then more of the drive's performance characteristics will come into play than just latency, so I don't see how that synthetic benchmark would bear much direct relation to the actual real-world experience. It's fine to show those latency benchmark results, but I don't think direct relations to the user experience can really be drawn from them.

    After toying with hundreds of SSDs, for me, I notice the difference in responsiveness between SATA and PCIe SSDs in day to day use. It's slight but noticeable, and especially so when launching apps after boot and moving a bunch of files around. You may not be able to draw conclusions by only looking at synthetic, but that doesn't mean one can't.

    The iometer and ATTO synthetic data are just a few of the data points I look at when analyzing performance. But, there are some relationships/patterns in these data points metrics that carry over to real-world performance. After analyzing the strengths and weaknesses between many SSDs architectures and performance scores and operation habits in the same system, one can start linking synthetic differences between devices to real-world experience differences between devices. As well, these results are included to validate manufacturer performance ratings. Real-world benchmarks can not do that, which is why I include them as supporting evidence to complement the real-world data.

    I'd like to see more real-world load time results in these reviews, as that's what these drives will typically be getting used for most of the time. As the Final Fantasy test shows, just because one drive appears multiple times as fast in some synthetic benchmarks or file copy tests, that doesn't necessarily translate to better performance at actually loading things. Practically all of the synthetic benchmarks show the P2 being substantially faster than an MX500 SATA drive, but when it comes to loading a game's files, it ends up being noticeably slower by a few seconds. Is that result a fluke, or are these synthetic tests really that out-of-touch with the drive's real-world performance? These reviews should measure other load times of common applications, games and so on, and not just rely primarily on pre-canned and synthetic benchmarks that seem to be at odds with the one real-world loading test.

    The only synthetic tests that I use are iometer and ATTO. PCMark 10 and SPECworkstation three are trace-based that test the SSD directly against multiple real-world workloads that cater to their respective consumer and prosumer market segments.

    Final fantasy shows just a second or two difference because of a few reasons. Most SSDs are similarly responsive to this one workload simply because it isn't a demanding one, it is a rather light read test really. Overall, the game data loading process is so well optimized for HDD usage that when you replace the HDD with the SSD, most will load the few hundred GB of data per game scene at relatively the same time since its such a small transfer.

    The fastest SSDs can respond faster to the random and sequential requests than others due to lower read request latency, and thus they rank ahead of slower ones here - those few hundredths of an ms add up to show that difference. Ideally, I need a larger, more graphically demanding game benchmark, a better GPU, and a 4K monitor to get a larger performance delta between drives. Different resolution settings and games will perform differently. I use Final Fantasy's benchmark because it is the only one I know of that saves load time data. I hope more devs could include load times in their game benchmarks. If you have any recommendations, I'm all ears!

    Also, I'd like to see test results for drives that are mostly full. Does the real-world performance tank if the drive is 75% or 90% full, and less space is dedicated to the SLC cache? These benchmark results don't really provide any good indication of that. The graphs showing how much performance drops once the cache is filled are nice, but the size of that cache will typically change as the drive is filled. A mostly-full drive may only have a handful of gigabytes of cache that gets filled even with moderately-sized write operations.

    Ah yes, more write cache testing, my favorite! I could do more and it would be cool to include, but it is not worth doing so at this time. Most dynamic SLC write caches will shrink at a higher full rate, but most perform well still. I perform all my testing on SSDs that are running the current OS and 50% full as it is (except the write cache testing is done empty after a secure erase when possible). Most of the time, even though the cache shrinks, it's still as responsive as when the drive was empty, the write cache is smaller in size so only larger transfers will be impacted.

    A "few MB" is kind of vague. How much system RAM is it actually using? The Crucual P1 had 1GB of DRAM onboard for each 1TB of storage capacity. If the P2 is using 1GB of system RAM for the same purpose, then that's a hidden cost not reflected by the price of the drive itself. This might be especially relevant if one were adding such a drive to a system with just 8GB of RAM. And even on a system with 16GB, that could become more of a concern within a few years as RAM requirements rise for things like games. If one ends up needing to upgrade their RAM sooner due to DRAMless drives consuming a chunk of it, then the cost savings of cutting that out of the drive itself seems questionable, especially given the effects on performance.
    Unfortunately, I do not have tools that tell me exactly how much each drive utilizes and manufacturers will not disclose specifics all the time...well I might have a tool, but I haven't been able to explore using it quite yet. From the drive's I have tested with HMB and had the RAM usage disclosed to me, it has been set to around 32-128MB. However, based on some discussion with a friend, we think it could be up to 2GB-4GB based on the spec's data

    And for that matter, it seems like the performance of system RAM could affect test results more than it does on drives with their own onboard RAM. I'm curious whether running system RAM at a lower speed, or perhaps on a Ryzen system with different memory latency characteristics could affect the standings for these DRAMless drives. The use of system RAM also undoubtedly affects the power test results as well. This drive appears to be among the most efficient models, but is the system RAM seeing higher power draw during file operations in its place?

    All testing is currently on an Asus X570 Crosshair VIIIHero (Wifi) + Ryzen R5 3600X @4.2 all core platform with a kit of 3600MHz CL18 DDR4. I actually have that suspicion myself and have been planning to get a faster kit of RAM to test out how it influences both DRAMless and DRAM-based SSD performance, too.
    Reply
  • MeeLee
    Price looks good. But I prefer to keep price lanes open for things that really need it, like GPUs, and run an SSD from the SATA port.
    Reply
  • cryoburner
    seanwebster said:
    The only synthetic tests that I use are iometer and ATTO. PCMark 10 and SPECworkstation three are trace-based that test the SSD directly against multiple real-world workloads that cater to their respective consumer and prosumer market segments.
    Yeah, I know those test suites are based on real-world software, but it's a bit vague exactly what operations each test is based on and how those apply to different workloads in the real world, so they might as well be synthetics. With CPU and graphics card reviews, you tend to see much more of a focus on testing actual software in ways that make it relatively clear what each test is comprised of.

    seanwebster said:
    Final fantasy shows just a second or two difference because of a few reasons. Most SSDs are similarly responsive to this one workload simply because it isn't a demanding one, it is a rather light read test really. Overall, the game data loading process is so well optimized for HDD usage that when you replace the HDD with the SSD, most will load the few hundred GB of data per game scene at relatively the same time since its such a small transfer.
    The Final Fantasy test usually seems to be relatively in line with typical measurements of NVMe vs SATA vs HDD performance as far as game loading is concerned, but the results for this drive seem a bit off, with it not even matching the MX500, despite practically all the other benchmarks in the review saying it should perform better. Maybe its a result of being DRAMless? If the game is heavily utilizing the CPU and RAM during the loading process, perhaps it's fighting with the drive for access to system memory? It might be something worth investigating further.

    seanwebster said:
    I use Final Fantasy's benchmark because it is the only one I know of that saves load time data. I hope more devs could include load times in their game benchmarks. If you have any recommendations, I'm all ears!
    I'm not really sure about any demanding games that include load time readouts. However, there could be other methods. For example, recording video of games loading with an external capture device and using the resulting video file to check how long loading took, though I can see how that might make testing a bit inconvenient. Or maybe just using a graph of disk access to check that, which would likely work reasonably well for at least some titles. There wouldn't necessarily need to be a lot of tests, but having a few might prevent any one from making a particular drive appear better or worse than might typically be the case.
    Reply
  • seanwebster
    cryoburner said:
    Yeah, I know those test suites are based on real-world software, but it's a bit vague exactly what operations each test is based on and how those apply to different workloads in the real world, so they might as well be synthetics. With CPU and graphics card reviews, you tend to see much more of a focus on testing actual software in ways that make it relatively clear what each test is comprised of.

    They are based on real-world system interaction and are traces that are exactly the same on each SSD. It is up to the storage device to differentiate itself when running those exact same workloads. There is some more detailed data in the results, but the time to spend on graphing out the details isn't. Most of the data shows similar to the rankings already graphed anyways. For more knowledge, you can read through the benchmark technical guides for more detailed information on how the tests run and how scoring is calculated. Storage tests are near the bottom of the tech guide.

    https://s3.amazonaws.com/download-aws.futuremark.com/pcmark10-technical-guide.pdf
    The Final Fantasy test usually seems to be relatively in line with typical measurements of NVMe vs SATA vs HDD performance as far as game loading is concerned, but the results for this drive seem a bit off, with it not even matching the MX500, despite practically all the other benchmarks in the review saying it should perform better. Maybe its a result of being DRAMless? If the game is heavily utilizing the CPU and RAM during the loading process, perhaps it's fighting with the drive for access to system memory? It might be something worth investigating further.

    Yes, entirely so. The firmware and HMB on Phison's E13T's optimized for write performance while Silicon Motion's SM2263XT's firmware and HMB is optimized for reading. Going from SSD controller though the PCIe lanes, to host memory for the buffer, and then, back to the controller adds a bunch of latency. Which is why the write-optimized E13T can't keep up in reading tasks, it is ready to respond to write requests more than it is ready to respond to read requests.
    Reply
  • logainofhades
    MeeLee said:
    Price looks good. But I prefer to keep price lanes open for things that really need it, like GPUs, and run an SSD from the SATA port.

    An M.2 PCI-E drive are not going to affect your top GPU slot, unless said board has a very weird configuration. Typically an M.2 will disable sata ports, or PCI-E slots that most people never really use much anyway. SLI/CF is dead, as well.
    Reply
  • MeeLee
    logainofhades said:
    An M.2 PCI-E drive are not going to affect your top GPU slot, unless said board has a very weird configuration. Typically an M.2 will disable sata ports, or PCI-E slots that most people never really use much anyway. SLI/CF is dead, as well.
    I run multiple GPUs, so PCIE lanes are still in short supply.
    For my purposes, I prefer to have PCIE 3.0 x8 slots, but can do with x4 lanes too.
    I use 3 GPUs, the max the motherboard supports.
    On an MSI MPG board i have, that means an x8/x8/x4 configuration, or 20 out of the 24 lanes.
    On other boards, I can only do x8/x4/x4 (or 16 lanes).
    In both cases that leaves either zero or 4 lanes left for (m.2) PCIE SSDs.
    Reply
  • logainofhades
    The top M.2 slot gets its lanes, from the CPU, at least on the AMD side of things. You get 16 lanes for GPU, 4 for M.2 NVME storage, and 4 that connect to the chipset. Any other M.2 is going to get it PCI-E lanes from the chipset. I am not aware of any current board that has a PLX chip, for more lanes. What lanes give what, with regards to M.2 and GPU lanes, beyond the top GPU and M.2, are dependent on chipset, and then how the board manufacturer decided to implement the lanes, they have to deal with.
    Reply
  • occational_gamer
    Buyer Be Warned: Crucial is now using lower density QLC chip, without any change in model numbers. Tom's re-reviewed the drives and changed its review to "do not recommend".

    Updated Review: https://www.tomshardware.com/features/crucial-p2-ssd-qlc-flash-swap-downgrade
    Reply