Original Link: https://www.anandtech.com/show/14661/usb32-g2-portable-ssds-roundup
USB 3.2 Gen 2 Portable SSDs Roundup - Featuring the Samsung T7 Touch and the SanDisk Extreme Pro
by Ganesh T S on January 23, 2020 9:00 AM EST
External bus-powered storage devices have grown both in storage capacity as well as speeds over the last decade. Thanks to rapid advancements in flash technology (including the advent of 3D NAND and NVMe) as well as faster host interfaces (such as Thunderbolt 3 and USB 3.x), we now have palm-sized flash-based storage devices capable of delivering 2GBps+ speeds. While those speeds can be achieved with Thunderbolt 3, mass-market devices have to rely on USB. Read on for a detailed review of the various high-speed external SSDs targeting the mainstream market.
Introduction
High-performance external storage devices use either Thunderbolt 3 or USB 3.2 Gen 2 for the host interface. Traditional SATA SSDs (saturating at 560 MBps) can hardly take full advantage of thebandwidth offered by USB 3.2 Gen 2. Last year, we took a look at a couple of NVMe to USB 3.2 Gen 2 enclosures from MyDigitalSSD and Plugable. Since then, we have had various leading vendors come out with their own solutions for this market segment. A steady stream of USB 3.2 Gen 2 external SSDs have been coming in to our lab over the last six months, with SanDisk's Extreme Pro Portable SSD and Samsung's Portable SSD T7 Touch (announced at CES) being the latest.
UL / Futuremark also updated their PCMark 10 benchmark with a storage bench recently. Our usual synthetic benchmarks - CrystalDiskMark and ATTO - have also had newer versions released since we last updated our benchmark suite for direct-attached storage devices in 2017. Over the winter holidays, we tweaked our evaluation suite and processed all the USB 3.2 Gen 2 SSDs that had come in over the preceding months through it.
The list of DAS units being reviewed today is provided below.
- Samsung Portable SSD T7 Touch 1TB
- SanDisk Extreme Pro Portable SSD 1TB
- Crucial Portable SSD X8 1TB
- DIY Plugable USBC-NVME and MyDigitalSSD SBX 1TB
- Lexar SL100 Pro 1TB
- OWC Envoy Pro EX USB-C 2TB
A quick overview of the internal capabilities of the storage devices is given by CrystalDiskInfo.
| Drive Information |
 |
CrystalDiskInfo allows us insight into the internal drive without opening up the unit. The most interesting aspects to note include the fact that UASP is supported by all drives, and all except the Plugable USBC-NVME and the Lexar SL100 Pro support NVMe 1.3.
Testbed Setup and Testing Methodology
Evaluation of DAS units on Windows is done with a Hades Canyon NUC configured as outlined below. We use one of the rear USB Type-C ports enabled by the Alpine Ridge controller for both Thunderbolt 3 and USB devices.
| AnandTech DAS Testbed Configuration | |
| Motherboard | Intel NUC8i7HVB |
| CPU | Intel Core i7-8809G Kaby Lake, 4C/8T, 3.1GHz (up to 4.2GHz), 14nm+, 8MB L2 |
| Memory | Crucial Technology Ballistix DDR4-2400 SODIMM 2 x 16GB @ 16-16-16-39 |
| OS Drive | Intel Optane SSD 800p SSDPEK1W120GA (118 GB; M.2 Type 2280 PCIe 3.0 x2 NVMe; Optane) |
| SATA Devices | Intel SSD 545s SSDSCKKW512G8 (512 GB; M.2 Type 2280 SATA III; Intel 64L 3D TLC) |
| Chassis | Hades Canyon NUC |
| PSU | Lite-On 230W External Power Brick |
| OS | Windows 10 Enterprise x64 (v1909) |
| Thanks to Intel for the build components | |
Our evaluation methodology for direct-attached storage devices adopts a judicious mix of synthetic and real-world workloads. While most DAS units targeting a particular market segment advertise similar performance numbers and also meet them for common workloads, the real differentiation is brought out on the technical side by the performance consistency metric and the effectiveness of the thermal solution. Industrial design and value-added features may also be important for certain users. The reamining sections in this review tackle all of these aspects after analyzing the features of the drives in detail.
Device Features and Characteristics
Prior to looking at the usage characteristics of the various drives, it is helpful to compare their specifications and also take a look at the internals. All the drives discussed in this review adopt the strategy of placing a NVMe SSD controller behind a USB 3.2 Gen 2 bridge chip.
| Direct-Attached Storage Characteristics | ||
| Aspect | ||
| Upstream Port | USB 3.2 Gen 2 Type-C | USB 3.2 Gen 2 Type-C |
| Bridge Chip | ASMedia ASM2362 | ASMedia ASM2362 |
| Power | Bus Powered | Bus Powered |
| Physical Dimensions | 85 mm x 57 mm x 8 mm | 96.2 mm x 49.6 mm x 8.9 mm |
| Weight | 58 grams (without cable) | 79 grams (without cable) |
| Cable | 30 cm USB 3.1 Gen 2 Type-C to Type-C 30 cm USB 3.1 Gen 2 Type-C to Type-A |
25 cm USB 3.1 Gen 2 Type-C to Type-C 25 cm USB 3.1 Gen 2 Type-C to Type-A |
| S.M.A.R.T Passthrough | Limited | Limited |
| UASP Support | Yes | Yes |
| TRIM Passthrough | Yes | Yes |
The table above shows that the Samsung Portable SSD T7 Touch is the lightest of the new lot, coming in at 58 grams. In contrast, the Crucial Portable SSD X8 and the OWC Envoy Pro EX USB-C come in at 148g and 100g - both of them feel solid in hand with an aesthetically pleasing industrial design. The physical dimensions indicate that the Samsung Portable SSD T7 Touch and the Lexar SL100 Pro do not integrate a standard M.2 2280 SSD. Both are credit-card sized units and small enough to unobtrusively fit in any pocket.
The Lexar SL100 Pro Portable SSD uses a JMicron JMS583 bridge chip (just like the Plugable USBC-NVME enclosure). All the other SSDs in the new set use the ASMedia ASM2362 bridge. While all units support some sort of SMART passthrough, most of the traditional SMART monitoring tools can't reliably track the internal SSD's parameters over the bridge chip. TRIM support exists in allof the drives.
Samsung Portable SSD T7 Touch
Samsung's T7 Touch is a unique DAS, thanks to its fingerprint security feature. We had already covered various aspects of the drive in our launch piece.
Another key aspect of the T7 Touch is the availability of support for use with both PCs and smartphones - as in, Samsung provides mobile apps keeping the security aspect in mind. We had already covered this while reviewing the Portable SSD T5, and the T7 Touch can be used in the same way. On the hardware side, we find that the fingerprint recognition module is embedded in the inside of the casing. There is only one internal board which carries the MZBLQ product tag. The SSD controller is the S4LR033, and the ASMedia ASM2362 bridge chip is right next to it. The flash package has the K9DVGY8J5A tag, which decodes as: TLC, 5th gen V-NAND (92L), 512Gbit per die, 16 dies, 1TB for the whole package. This is the same NAND package used in 2TB 970 EVO Plus.
The thermal design also appears to tick all the right boxes - aluminum casing with a pink thermal pad (Samsung terms it as ePCM - encapsulated phase change materials) covering all the heat-generating PCB components. During operation, the LED around the fingerprint sensor lights up and rotates. The LED automatically turns off after the drive idles for 10 seconds. A blinking on/off status indicates that a security unlock is needed. All that said, it is possible to also use the T7 Touch as a dumb DAS without any of these security features activated.
SanDisk Extreme Pro Portable SSD
SanDisk's Extreme Pro Portable SSD carries forward the gumstick form-factor that has served the previous Extreme Portable SSD models well. The key difference is that the fully plastic enclosure in the previous generation is replaced by a combination of plastic and aluminum.
SanDisk is now supplying two distinct cables (Type-C to Type-C, and, Type-C to Type-A) with the Extreme Pro, compared to the Type-C to Type-C and Type-C to Type-A adapter scheme used in previous SSDs. Internally, we see a wrapper around the mainboard (with the ASMedia ASM2362bridge chip and a Type-C port that is also protected by a gasket to prevent water ingress) with a single thermal pad in it. A WD Black NVMe SSD acts as a daughterboard. SanDisk also claims IP55 ratings for dust and water resistance.
Lexar SL100 Pro Portable SSD
Lexar's SL100 Pro adopts the same single-board strategy as the Samsung T7 Touch, enabling it to come in a more compact form-factor compared to the gum-stick offerings. The SSD controller is from Marvell and the bridge chip is the JMicron JMS583.
While most other USB 3.2 Gen 2 SSDs claim speeds of up to 1050 MBps, Lexar is conservative and claims speeds of up to 950 MBps only.
Crucial Portable SSD X8
The Portable SSD X8 is the only device being considered today to come with QLC memory. The device places their Pl NVMe SSD behind an ASMedia ASM2362 bridge chip.
It comes with a single Type-C to Type-C cable and a bundled Type-C to Type-A adapter. The unit proved quite difficult to disassemble, and we do not have any teardown photos of the device.
OWC Envoy Pro EX USB-C
The OWC Envoy Pro EX USB-C is available either driveless, or, with an OWC Aura P12 NVMe SSD pre-installed. Our review version came with a 2TB P12.
The enclosure is fully metallic and the single thermal pad affixed to the casing along the length of the M.2 drive is good enough to draw away the heat generated in the course of usage.
Synthetic Benchmarks - ATTO and CrystalDiskMark
Most USB 3.2 Gen 2 NVMe-based SSDs claim read speeds of up to 1050 MBps and write speeds of up to 1000 MBps. Most of these claims are backed up by the ATTO benchmarks provided below. Unfortunately, these access traces are not very common in real-life scenarios.
| Drive Performance Benchmarks - CrystalDiskMark |
 |
Read speeds saturate around 1020 MBps for most drives, and writes around 900 MBps. The T7 Touch appears to lag behind the rest a bit in all the workloads, while remaining in the same ballpark.
AnandTech DAS Suite - Benchmarking for Performance Consistency
Our testing methodology for DAS 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 DAS as a download or install location for games and importing files directly off the DAS 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 three different workloads:
- Photos: 15.6 GB collection of 4320 photos (RAW as well as JPEGs) in 61 sub-folders
- Videos: 16.1 GB collection of 244 videos (MP4 as well as MOVs) in 6 sub-folders
- BR: 10.7 GB Blu-ray folder structure of the IDT Benchmark Blu-ray
Each workload's data set is first placed in a 25GB RAM drive, and a robocopy command is issued to transfer it to the DAS under test (formatted in NTFS). Upon completion of the transfer (write test), the contents from the DAS are read back into the RAM drive (read test). 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. Bandwidth for each data set is computed as the average of all three passes.
| Performance Consistency and Thermal Characteristics |
 |
The first three sets of writes and reads correspond to the photos 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 video suite. Another small RAM-drive transfer gap is followed by three sets for the Blu-ray folder. An important point to note here is that each of the first three blue and green areas correspond to 15.6 GB of writes and reads respectively. Of all the tested drives, only the Crucial Portable SSD X8 hiccups a little during certain writes. Temperature-wise, the OWC Envoy Pro EX USB-C and the Samsung T7 Touch both show only a 3C increase in temperature on eithe side of the workload. On the other hand, the Lexar SL100 Pro shows a significant 11C increase, pointing to possible thermal issues in the long run.
PCMark 10 Storage Bench - Real-World Access Traces
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 opted 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.
With an overall PCMark 10 full system drive benchmark score of 561, the T7 Touch comes in last among the considered DAS devices. The Extreme Pro scores a more respectable 683, but the Crucial X8 leas the pack with a 765.
Miscellaneous Aspects and Concluding Remarks
The performance of the drives 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.
| Drive Power Consumption - CrystalDiskMark Workloads |
 |
The Samsung Portable SSD T7 Touch's race to idle is the most interesting aspect decipherable from the above results. At just 570 mW idle power consumption, the T7 Touch is a winner when used with a battery-powered host. The peak power consumption is also below 4.5W. The OWC Envoy Pro EX USB-C does go beyond 6W, but, only for a very brief while.
Pricing
The price of flash-based storage devices tend to fluctuate quite a bit over time. However, the relative difference between different models usually doesn't change. The table below summarizes the product links and pricing for the various units discussed in the review.
| External Flash Storage Devices - Pricing | ||||
| Product | Model Number | Capacity (GB) | Street Price (USD) | Price per GB (USD/GB) |
| DIY Plugable USBC-NVME and MyDigitalSSD SBX 1TB | USBC-NVME | 960 | $140 | 0.15 |
| Crucial Portable SSD X8 1TB | CT1000X8SSD9 | 1000 | $165 | 0.17 |
| Lexar SL100 Pro 1TB | LSL100P-1TBRBNA | 1000 | $179 | 0.18 |
| Samsung Portable SSD T7 Touch 1TB | MU-PC1T0S/WW | 1000 | $230 | 0.23 |
| SanDisk Extreme Pro Portable SSD 1TB | SDSSDE80-1T00-A25 | 1000 | $230 | 0.23 |
| OWC Envoy Pro EX USB-C 2TB | ENVPROC2N20 | 1920 | $450 | 0.23 |
A DIY build is cheap, but can suffer from improper thermals. The X8, with its QLC memory is the cheapest off-the-shelf USB 3.2 Gen 2 SSD, followed closely by the Lexar SL100 Pro. However, both of them are not impressive when it comes to performance consistency for power users. The Extreme Pro and the T7 Touch are priced the same at $0.23/GB.
Final Words
After careful analysis of various aspects (including benchmark numbers, temperatures, and power consumption), it is clear that there is no single DAS unit that wins on all metrics.
Casual users looking for a cheap deal could go in for the X8 - it does win on a lot of benchmarks. However, power users would do well to stay away from it because the performance of the unit is abysmal after the SLC cache runs out.
Users looking for a secure, yet easy to use DAS or those looking for DAS units to use mainly with battery-operated devices should go for the Samsung T7 Touch. Its fingerprint security feature is easy to use, as there is no need to remember passwords. Its thermal design and power consumption profiles are also excellent. The only drawback is that the performance doesn't match up to other devices in the fray.
The OWC Envoy Pro EX has an attractive industrial design and exhibits great performance consistency. Its benchmark numbers are also good, but, given that we evaluated a 2TB model, it is not exactly an apples-to-apples comparison with the other drives.
From the viewpoint of raw performance for power users, our recommendation would go to the SanDisk Extreme Pro Portable SSD. Our only gripe is that its thermal design could do with some improvement.
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