The increasing popularity of portable SSDs has prompted almost all tier-one NAND flash manufacturers to jump into the market. Over the last decade, both Samsung and SanDisk / Western Digital have been presenting consumers with a range of PSSD offerings targeting different sub-segments. On the other hand, the flash-based storage lineup from Crucial (Micron's consumer-facing brand) has had a distinctive focus on internal SSDs. The company introduced its first PSSD only in 2019 (the X6), and followed it up with the X8 a year later. Both these drives used QLC NAND, making it suitable only for mainstream consumers on a budget.

The company shifted focus to power users in the PSSD segment earlier this year with the launch of two new products - the USB 3.2 Gen 2 X9 Pro, and the USB 3.2 Gen 2x2 X10 Pro. These 1 GBps and 2 GBps-class drives come with a Type-C port and a Type-C to Type-C cable (Type-A adapter sold separately). The performance specifications of these two products indicate suitability for power users - for the first time, the company is quoting write speeds for their PSSDs in the marketing material.

We had taken a comprehensive look at the 2TB version of the X9 Pro in August. Following that review, Crucial sampled us all three capacity points of the X10 Pro to put through the same evaluation routine. This review takes a detailed look at the performance and value proposition of the different X10 Pro SKUs, with a particular focus on how they stack up against the existing players at each capacity point.


Introduction and Product Impressions

Portable SSDs have gained rapid market presence, thanks to advancements in flash technology and the appearance of fast host interfaces for external devices. This has enabled the product category to appeal to a wide range of users with different budgets and performance requirements. Continued technological progress on both fronts has resulted in bus-powered direct-attached storage devices growing in both storage capacity and speeds. The Type-C standard has also achieved widespread acceptance in the consumer market. Protocols such as USB 3.2 Gen 2x2 / USB4 and Thunderbolt riding on top of the Type-C connector have enabled the introduction of palm-sized flash-based storage devices capable of delivering 20 Gbps (2 GBps+) speeds.

The thermal aspect is an important consideration for high-speed storage devices. Bridge-based solutions with multiple protocol conversion chips generally dissipate more power due to the additional components. High-performance portable SSDs in the past have had no option but to use them - first, with SATA bridges, and then with NVMe bridges. The introduction of native UFD controllers capable of hitting 10 Gbps and 20 Gbps from Phison and Silicon Motion has opened up yet another option in this category. The Crucial X6, equipped with the Phison U17, was reviewed in August 2021 and was one of the first retail products to surpass the SATA speeds barrier by hitting 800 MBps speeds without using a NVMe bridge. Around the same time, Silicon Motion's SM2320 powered the Kingston XS2000 to 20 Gbps speeds without using a bridge chip.

Products based on Silicon Motion's SM2320 have gained a lot of consumer mindshare because they have typically been able to hit the interface speed limits for sequential accesses in both the 10 Gbps and 20 Gbps categories. However, consistency was an issue as the initial wave of products used Micron's 96L 3D TLC or BiCS 4 / BiCS 5 (up to 112L) 3D TLC NAND. The introduction of faster flash has since allowed portable SSDs (PSSDs) based on the native UFD controllers to hit higher speeds and maintain them even in direct-to-TLC scenarios.

The X10 Pro units we are looking at in this review are 42g 65mm x 50mm USB 3.2 Gen 2x2 PSSDs made of anodized aluminum. They includes a lanyard hole (with the LED near the hole, rather than near the Type-C port) and a rubberized soft-touch base for protection against bumps. The sides are slightly recessed for better traction during handling. Similar to the X9 Pro, the X10 Pro is also IP55 rated, and drop-proof up to 7.5'. The packaging is minimal - a short USB 3.2 Gen 2 Type-C to Type-C cable and a user guide in addition to the main unit.

Similar to the X9 Pro, the X10 Pro also uses the Silicon Motion SM2320 native controller (albeit, in a 20 Gbps USB 3.2 Gen 2x2 configuration) along with Micron's 176L 3D TLC NAND packages.

CrystalDiskInfo provides a quick overview of the capabilities of the internal storage device. TRIM and NCQ are not seen in the features list, though we have seen those available in other PSSDs based on the Silicon Motion SM2320. However, we did confirm that TRIM was actually supported using the Windows Optimize-Volume ReTrim option for all the X10 Pro SKUs. The benchmark numbers in the next section also show that native command queuing is active in the PSSD, and all S.M.A.R.T features such as temperature read outs worked well.

S.M.A.R.T Passthrough - CrystalDiskInfo

The table below presents a comparative view of the specifications of the different storage bridges presented in this review.

Comparative Direct-Attached Storage Devices Configuration
Downstream Port Native Flash Native Flash
Upstream Port USB 3.2 Gen 2x2 Type-C (Female) USB 3.2 Gen 2x2 Type-C (Female)
Bridge Chip Silicon Motion SM2320 Silicon Motion SM2320
Power Bus Powered Bus Powered
Use Case 2GBps-class, sturdy palm-sized high-performance portable SSD with a Type-C interface 2GBps-class, sturdy palm-sized high-performance portable SSD with a Type-C interface
Physical Dimensions 65 mm x 50 mm x 10 mm 65 mm x 50 mm x 10 mm
Weight 42 grams 42 grams
Cable 22 cm USB 3.2 Gen 2x2 Type-C (male) to Type-C (male) 22 cm USB 3.2 Gen 2x2 Type-C (male) to Type-C (male)
S.M.A.R.T Passthrough Yes Yes
UASP Support Yes Yes
TRIM Passthrough Yes Yes
Hardware Encryption Yes Yes
Evaluated Storage Micron B47R 176L 3D TLC Micron B47R 176L 3D TLC
Price $290 $169
Review Link Crucial X10 Pro 4TB Review Crucial X10 Pro 2TB Review

Prior to looking at the benchmark numbers, power consumption, and thermal solution effectiveness, a description of the testbed setup and evaluation methodology is provided.

Testbed Setup and Evaluation Methodology

Direct-attached storage devices (including thumb drives) are evaluated using the Quartz Canyon NUC (essentially, the Xeon / ECC version of the Ghost Canyon NUC) configured with 2x 16GB DDR4-2667 ECC SODIMMs and a PCIe 3.0 x4 NVMe SSD - the IM2P33E8 1TB from ADATA.

The most attractive aspect of the Quartz Canyon NUC is the presence of two PCIe slots (electrically, x16 and x4) for add-in cards. In the absence of a discrete GPU - for which there is no need in a DAS testbed - both slots are available. In fact, we also added a spare SanDisk Extreme PRO M.2 NVMe SSD to the CPU direct-attached M.2 22110 slot in the baseboard in order to avoid DMI bottlenecks when evaluating Thunderbolt 3 devices. This still allows for two add-in cards operating at x8 (x16 electrical) and x4 (x4 electrical). Since the Quartz Canyon NUC doesn't have a native USB 3.2 Gen 2x2 port, Silverstone's SST-ECU06 add-in card was installed in the x4 slot. All non-Thunderbolt devices are tested using the Type-C port enabled by the SST-ECU06.

The specifications of the testbed are summarized in the table below:

The 2021 AnandTech DAS Testbed Configuration
System Intel Quartz Canyon NUC9vXQNX
CPU Intel Xeon E-2286M
Memory ADATA Industrial AD4B3200716G22
32 GB (2x 16GB)
DDR4-3200 ECC @ 22-22-22-52
OS Drive ADATA Industrial IM2P33E8 NVMe 1TB
Secondary Drive SanDisk Extreme PRO M.2 NVMe 3D SSD 1TB
Add-on Card SilverStone Tek SST-ECU06 USB 3.2 Gen 2x2 Type-C Host
OS Windows 10 Enterprise x64 (21H1)
Thanks to ADATA, Intel, and SilverStone Tek for the build components

The testbed hardware is only one segment of the evaluation. Over the last few years, the typical direct-attached storage workloads for memory cards have also evolved. High bit-rate 4K videos at 60fps have become quite common, and 8K videos are starting to make an appearance. Game install sizes have also grown steadily even in portable game consoles, thanks to high resolution textures and artwork. Keeping these in mind, our evaluation scheme for portable SSDs and UFDs involves multiple workloads which are described in detail in the corresponding sections.

  • Synthetic workloads using CrystalDiskMark and ATTO
  • Real-world access traces using PCMark 10's storage benchmark
  • Custom robocopy workloads reflective of typical DAS usage
  • Sequential write stress test

In the next couple of sections, we have an overview of the performance of the three X10 Pro PSSDs in these benchmarks. Prior to providing concluding remarks, we have some observations on the drives' power consumption numbers and thermal solution also.

Performance Benchmarks
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  • SanX - Friday, November 10, 2023 - link

    Time for 40gbit/s devices and USB4. They are already sold on Amazon, though price is a bit too high around $120-150.
    As to the disks of this article -- all they show good numbers in CrystalDiskMark but in reality 10Gbit/s devices will show transfer/copy data speeds like current harddrives 250MB/s , and 20Gbit/s ones like the older serial SSDs (500MB/s), which is hell slow and annoying. after you have seen speeds of NVMe on PCIe 4.0 around 3 GB/s, and PCIe5.0 probably get you double that
  • Jansen - Friday, November 10, 2023 - link

    8TB version would be great. Let’s encourage larger capacities please.
  • linuxgeex - Friday, November 10, 2023 - link

    I think the author is imagining that non-mainstream users buying USB external disks are going to use them for mission-critical high-IOPS DB write workloads such that they can actually wear out the QLC storage with an abundance of writes, and simultaneously they have forgotten that today's QLC has the same TBW ratios as early eTLC drives, which as the name suggests, was used in Enterprise.

    In reality even professional users won't be subjecting an external SSD to punishing high-IOPS write workloads. They will write maybe 200GB in a day, and a 600TBW rating will last them 10 years.
  • FunBunny2 - Saturday, November 11, 2023 - link

    today's QLC has the same TBW ratios as early eTLC drives, which as the name suggests, was used in Enterprise.

    well... Enterprise use cares not about longevity, only that those XX,000,000 drives they bought don't fail before the warranty claims. Enterprise backs up at fetish levels, and swaps out devices just before warranty use is reached. if a QLC SSD is ten cents cheaper than a TLC drive in the same warranty period, they'll buy it. if the QLC has a 3 year warranty and the TLC a 5 year warranty, and the QLC is $X cheaper, then Enterprise will load up; otherwise not.

    consumer-users, generally, just don't behave that way.
  • Hresna - Saturday, November 11, 2023 - link

    What’s the explanation for the wildly different write bandwidths based on file type? I’m aware of performance penalties for trying to write lots of small files versus large ones, but I would think that video writing and iso writing should be pretty similar as a workload.

    A practical and “mission critical” use case for high write speeds is recording high bitrate video direct from camera… if you start dropping frames, the device is essentially useless in a professional setting. Camera data rates are getting hunger and higher with intraframe and raw 6k / 8k becoming more common.
  • wr3zzz - Sunday, November 12, 2023 - link

    I stop shopping for portable SSD faster than 800MB/s after realizing the time I spent trying to get the right port for maximum speed is more than the time saving I could get from a theoretically faster but certainly more expensive portable SSD.
  • MDD1963 - Thursday, November 16, 2023 - link

    "Booting Windows 10

    The read-write bandwidth recorded for each drive in the *boo* access trace is presented below."

    Boo access is important! :)
  • GreenReaper - Tuesday, November 21, 2023 - link

    Go for the ICs, Boo - go for the ICs!

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