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 2×2 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.
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 2×2 / 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 2×2 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 2×2 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
|USB 3.2 Gen 2×2 Type-C (Female)
|USB 3.2 Gen 2×2 Type-C (Female)
|Silicon Motion SM2320
|Silicon Motion SM2320
|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
|65 mm x 50 mm x 10 mm
|65 mm x 50 mm x 10 mm
|22 cm USB 3.2 Gen 2×2 Type-C (male) to Type-C (male)
|22 cm USB 3.2 Gen 2×2 Type-C (male) to Type-C (male)
|Micron B47R 176L 3D TLC
|Micron B47R 176L 3D TLC
|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 2×2 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
|Intel Quartz Canyon NUC9vXQNX
|Intel Xeon E-2286M
|ADATA Industrial AD4B3200716G22
32 GB (2x 16GB)
DDR4-3200 ECC @ 22-22-22-52
|ADATA Industrial IM2P33E8 NVMe 1TB
|SanDisk Extreme PRO M.2 NVMe 3D SSD 1TB
|SilverStone Tek SST-ECU06 USB 3.2 Gen 2×2 Type-C Host
|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.
Benchmarks such as ATTO and CrystalDiskMark help provide a quick look at the performance of the direct-attached storage device. The results translate to the instantaneous performance numbers that consumers can expect for specific workloads, but do not account for changes in behavior when the unit is subject to long-term conditioning and/or thermal throttling. Yet another use of these synthetic benchmarks is the ability to gather information regarding support for specific storage device features that affect performance.
Crucial claims read and write speeds of 2100 MBps and 2000 MBps respectively for all three SKUs. We do get numbers close to those in the ATTO benchmarks presented below. Our ATTO benchmarking is restricted to a single configuration in terms of queue depth, and is only representative of a small sub-set of real-world workloads. As such, the used configuration can’t back up Crucial’s claims completely. However, the results do allow the visualization of change in transfer rates as the I/O size changes, with optimal performance being reached around 512 KB for a queue depth of 4 across all the capacity points.
CrystalDiskMark uses four different access traces for reads and writes over a configurable region size. Two of the traces are sequential accesses, while two are 4K random accesses. Internally, CrystalDiskMark uses the Microsoft DiskSpd storage testing tool. The ‘Seq128K Q32T1’ sequential traces use 128K block size with a queue depth of 32 from a single thread, while the ‘4K Q32T16’ one does random 4K accesses with the same queue configuration, but from multiple threads. The ‘Seq1M’ traces use a 1MiB block size. The plain ‘Rnd4K’ one uses only a single queue and single thread . Comparing the ‘4K Q32T16’ and ‘4K Q1T1’ numbers can quickly tell us whether the storage device supports NCQ (native command queuing) / UASP (USB-attached SCSI protocol). If the numbers for the two access traces are in the same ballpark, NCQ / UASP is not supported. This assumes that the host port / drivers on the PC support UASP.
Sequential reads match Crucial’s claims at a queue depth of 8 for all three models. Sequential writes top out around 1750 MBps for the 4TB SKU, but drops down to around 1600 MBps for the 1TB version. On the random access front, we see a marked increase in IOPS when moving from a queue depth of 1 to 32, indicating that NCQ is active and working well.
Competitive analysis will be dealt with in subsequent sections, but it makes sense to point out that the sequential read numbers are not markedly different for the considered PSSDs. Writes are a different story, with the native UFD controller-based units bunched at the mid-range (between 1500 – 1750 MBps). The bridge-based PSSDs with DRAM-equipped internal units are able to hit the 2 GBps number. Ones using a DRAM-less platform with the bridge (such as the Samsung T9) hit around 1.9 GBps. The high queue-depth random reads are better in the T9, but that platform / firmware doesn’t seem to be optimized for writes with similar characteristics, and comes in with less than a third of the IOPS of the equivalent Crucial X10 Pro.
Our testing methodology for storage bridges / direct-attached storage units takes into consideration the usual use-case for such devices. The most common usage scenario is transfer of large amounts of photos and videos to and from the unit. Other usage scenarios include the use of the unit as a download or install location for games and importing files directly from it into a multimedia editing program such as Adobe Photoshop. Some users may even opt to boot an OS off an external storage device.
The AnandTech DAS Suite tackles the first use-case. The evaluation involves processing five different workloads:
- AV: Multimedia content with audio and video files totalling 24.03 GB over 1263 files in 109 sub-folders
- Home: Photos and document files totalling 18.86 GB over 7627 files in 382 sub-folders
- BR: Blu-ray folder structure totalling 23.09 GB over 111 files in 10 sub-folders
- ISOs: OS installation files (ISOs) totalling 28.61 GB over 4 files in one folder
- Disk-to-Disk: Addition of 223.32 GB spread over 171 files in 29 sub-folders to the above four workloads (total of 317.91 GB over 9176 files in 535 sub-folders)
Except for the ‘Disk-to-Disk’ workload, each data set is first placed in a 29GB RAM drive, and a robocopy command is issue to transfer it to the external storage unit (formatted in exFAT for flash-based units, and NTFS for HDD-based units).
robocopy /NP /MIR /NFL /J /NDL /MT:32 $SRC_PATH $DEST_PATH
Upon completion of the transfer (write test), the contents from the unit are read back into the RAM drive (read test) after a 10 second idling interval. This process is repeated three times for each workload. Read and write speeds, as well as the time taken to complete each pass are recorded. Whenever possible, the temperature of the external storage device is recorded during the idling intervals. Bandwidth for each data set is computed as the average of all three passes.
The ‘Disk-to-Disk’ workload involves a similar process, but with one iteration only. The data is copied to the external unit from the CPU-attached NVMe drive, and then copied back to the internal drive. It does include more amount of continuous data transfer in a single direction, as data that doesn’t fit in the RAM drive is also part of the workload set.
It can be seen that there is no significant gulf in the numbers between the different units in the read workloads. For all practical purposes, the casual user will notice no difference between them in the course of normal usage. However, writes are a completely different story. The three X10 Pro SKUs come in the bottom half of the graphs, and present widely varying numbers. As we find further down in our evaluation of the performance consistency, the SKUs – particularly the 1TB variant – can start to exhibit performance loss after being subject to repeated stress.
Power users may want to dig deeper to understand the limits of each device. To address this concern, we also instrumented our evaluation scheme for determining performance consistency.
Aspects influencing the performance consistency include SLC caching and thermal throttling / firmware caps on access rates to avoid overheating. This is important for power users, as the last thing that they want to see when copying over 100s of GB of data is the transfer rate going down to USB 2.0 speeds.
In addition to tracking the instantaneous read and write speeds of the DAS when processing the AnandTech DAS Suite, the temperature of the drive was also recorded. In earlier reviews, we used to track the temperature all through. However, we have observed that SMART read-outs for the temperature in NVMe SSDs using USB 3.2 Gen 2 bridge chips end up negatively affecting the actual transfer rates. To avoid this problem, we have restricted ourselves to recording the temperature only during the idling intervals. The graphs below present the recorded data.
|AnandTech DAS Suite – Performance Consistency
The first three sets of writes and reads correspond to the AV suite. A small gap (for the transfer of the video suite from the internal SSD to the RAM drive) is followed by three sets for the Home suite. Another small RAM-drive transfer gap is followed by three sets for the Blu-ray folder. This is followed up with the large-sized ISO files set. Finally, we have the single disk-to-disk transfer set.
While the initial sets perform creditably in terms of consistency, we see cracks start to appear during the disk-to-disk transfer set. Instantaneous write speeds go as low as 50 MBps and this loss is particularly brutal for the 1TB version. The transfer of around 318 GB takes as much as 20 minutes in the 1TB version, compared to around 5 minutes for the 4TB one and around 6 minutes for the 2TB SKU. Thermal throttling, thankfully, doesn’t seem to be the issue, as we see temperatures topping out at just 56C (across all SKUs) during the course of this test.
There are a number of storage benchmarks that can subject a device to artificial access traces by varying the mix of reads and writes, the access block sizes, and the queue depth / number of outstanding data requests. We saw results from two popular ones – ATTO, and CrystalDiskMark – in a previous section. More serious benchmarks, however, actually replicate access traces from real-world workloads to determine the suitability of a particular device for a particular workload. Real-world access traces may be used for simulating the behavior of computing activities that are limited by storage performance. Examples include booting an operating system or loading a particular game from the disk.
PCMark 10’s storage bench (introduced in v2.1.2153) includes four storage benchmarks that use relevant real-world traces from popular applications and common tasks to fully test the performance of the latest modern drives:
- The Full System Drive Benchmark uses a wide-ranging set of real-world traces from popular applications and common tasks to fully test the performance of the fastest modern drives. It involves a total of 204 GB of write traffic.
- The Quick System Drive Benchmark is a shorter test with a smaller set of less demanding real-world traces. It subjects the device to 23 GB of writes.
- The Data Drive Benchmark is designed to test drives that are used for storing files rather than applications. These typically include NAS drives, USB sticks, memory cards, and other external storage devices. The device is subjected to 15 GB of writes.
- The Drive Performance Consistency Test is a long-running and extremely demanding test with a heavy, continuous load for expert users. In-depth reporting shows how the performance of the drive varies under different conditions. This writes more than 23 TB of data to the drive.
Despite the data drive benchmark appearing most suitable for testing direct-attached storage, we opt to run the full system drive benchmark as part of our evaluation flow. Many of us use portable flash drives as boot drives and storage for Steam games. These types of use-cases are addressed only in the full system drive benchmark.
The Full System Drive Benchmark comprises of 23 different traces. For the purpose of presenting results, we classify them under five different categories:
- Boot: Replay of storage access trace recorded while booting Windows 10
- Creative: Replay of storage access traces recorded during the start up and usage of Adobe applications such as Acrobat, After Effects, Illustrator, Premiere Pro, Lightroom, and Photoshop.
- Office: Replay of storage access traces recorded during the usage of Microsoft Office applications such as Excel and Powerpoint.
- Gaming: Replay of storage access traces recorded during the start up of games such as Battlefield V, Call of Duty Black Ops 4, and Overwatch.
- File Transfers: Replay of storage access traces (Write-Only, Read-Write, and Read-Only) recorded during the transfer of data such as ISOs and photographs.
PCMark 10 also generates an overall score, bandwidth, and average latency number for quick comparison of different drives. The sub-sections in the rest of the page reference the access traces specified in the PCMark 10 Technical Guide.
Booting Windows 10
The read-write bandwidth recorded for each drive in the boo access trace is presented below.
Low queue depth random accesses usually get better performance with DRAM-equipped SSDs using dedicated high-performance NVMe SSD controllers. So, it is not a surprise that the SM2320-equipped Crucial X10 Pro SKUs can only deliver passable performance as a boot drive, making up the bottom half of the pack.
The read-write bandwidth recorded for each drive in the sacr, saft, sill, spre, slig, sps, aft, exc, ill, ind, psh, and psl access traces are presented below.
The X10 Pro SKUs fare much better for creative workloads, as many of the traces are sequential in nature. This allows the SKUs to make up the middle of the pack, with the 4TB version edging out the lower capacity points comfortably. Bridge-based solutions still deliver better overall performance for these workloads.
The read-write bandwidth recorded for each drive in the exc and pow access traces are presented below.
The 4TB version again performs much better for the spreadsheet workload, making it to the top two while edging out even the bridge-based solutions. However, the performance of all three SKUs for the presentation workload lands them in the second half.
The read-write bandwidth recorded for each drive in the bf, cod, and ow access traces are presented below.
Gaming workloads are usually heavy on sequential reads, though throwing different file sizes into the mix may result in unexpected performance losses. While the Battlefield V workload sees the X10 Pro SKUs in the top half, the other two workloads see them slipping down.
Files Transfer Workloads
The read-write bandwidth recorded for each drive in the cp1, cp2, cp3, cps1, cps2, and cps3 access traces are presented below.
Pure large-sized reads work well for the X10 Pro SKUs. However, the insertion of smaller file sizes brings them down to the middle of the pack, and the mixture of both reads and writes pushes them down to the very bottom. This behavior is only to be expected from PSSDs based on DRAM-less native UFD controllers, particularly when the comparison mix includes high-end bridge-based solutions.
PCMark 10 reports an overall score based on the observed bandwidth and access times for the full workload set. The score, bandwidth, and average access latency for each of the drives are presented below.
The three SKUs appear in the bottom half of the pack, with the 4TB version slotting in just below the recently-introduced bridge-based DRAM-less Samsung T9. This is a creditable result, given that the mix includes high-end bridge-based solutions.
The performance of the three different Crucial X10 Pro PSSDs in various real-world access traces as well as synthetic workloads was brought out in the preceding sections. We also looked at the performance consistency for these cases. Power users may also be interested in performance consistency under worst-case conditions, as well as drive power consumption. The latter is also important when used with battery powered devices such as notebooks and smartphones. Pricing is also an important aspect. We analyze each of these in detail below.
Worst-Case Performance Consistency
Flash-based storage devices tend to slow down in unpredictable ways when subject to a large number of small-sized random writes. Many benchmarks use that scheme to pre-condition devices prior to the actual testing in order to get a worst-case representative number. Fortunately, such workloads are uncommon for direct-attached storage devices, where workloads are largely sequential in nature. Use of SLC caching as well as firmware caps to prevent overheating may cause drop in write speeds when a flash-based DAS device is subject to sustained sequential writes.
Our Sequential Writes Performance Consistency Test configures the device as a raw physical disk (after deleting configured volumes). A fio workload is set up to write sequential data to the raw drive with a block size of 128K and iodepth of 32 to cover 90% of the drive capacity. The internal temperature is recorded at either end of the workload, while the instantaneous write data rate and cumulative total write data amount are recorded at 1-second intervals.
|Sequential Writes to 90% Capacity – Performance Consistency
The 4TB version can sustain around 1600 MBps for the duration of the test, while ending up at 70C. On the other hand, the 2TB version starts out similarly but drops down to 1300 MBps after around 10 minutes. Both the 1TB and 2TB versions ended up around 65C. However, the 1TB variant dropped down from 1600 MBps to 1200 MBps within a few seconds of starting the test. The reason for this is likely to be the history of write accesses putting the controller in a rather fragile state, rather than thermal throttling.
Bus-powered devices can configure themselves to operate within the power delivery constraints of the host port. While Thunderbolt ports are guaranteed to supply up to 15W for client devices, USB 2.0 ports are guaranteed to deliver only 2.5W (500mA @ 5V). In this context, it is interesting to have a fine-grained look at the power consumption profile of the various external drives. Using the ChargerLAB KM003C, the bus power consumption of the drives was tracked while processing the CrystalDiskMark workloads (separated by 5s intervals). The graphs below plot the instantaneous bus power consumption against time, while singling out the maximum and minimum power consumption numbers.
|CrystalDiskMark Workloads – Power Consumption
The average power consumption during the active stage is around 2W, compared to the 3W idling number for the best overall performer of them all – the SanDisk Extreme Pro v2. When operating with battery-powered devices, the Crucial X10 Pro is undoubtedly an excellent choice.
The flash market is currently experiencing a supply glut, with pricing to the advantage of the consumers. Crucial launched the 4TB version of the X10 Pro at ‘$290, and the pricing has held steady since then. There is a slight premium over the X9 Pro, but that is only to be expected for the performance jump. At 7.25¢ / GB, the PSSD presents excellent value for money. Other capacity points come in at ‘$169 (8.5¢/GB) and $120 (12¢/GB) . The 1TB variant’s performance consistency is not as good as expected – the 2TB and 4TB versions present a better value proposition.
The bridge-based PSSDs presented as comparison units are more of a premium offering, though we see the much-maligned SanDisk Extreme Portable v2 being priced as low as $300. From a pure performance viewpoint, it is hard to recommend against the SanDisk PSSD if the 3-2-1 backup strategy is being observed. However, the X10 Pro SKUs score in the power consumption and physical footprint aspects. Crucial is also throwing in some value-adds such as the Mylio Photos+ trial subscription into the mix. Overall performance across a variety of workloads may not favor the X10 Pro SKUs when bridge-based PSSDs are in the picture. However, for the vast majority of direct-attached storage use-cases, the performance profile, physical footprint, case design, and pricing of the 4TB and 2TB Crucial X10 Pro SKUs represent an optimal combination. The 1TB version can be recommended for entry-level use-cases, but needs to be priced a bit lower keeping its performance consistency issues in mind.