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.


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
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  • lilkwarrior - Thursday, January 23, 2020 - link

    Seems pointless to not be Thunderbolt 3 or USB4.
  • avbohemen - Thursday, January 23, 2020 - link

    I wonder what the limit is in the atto/as-ssd iops test. All drives hit a limit of 23-25k 4kB iops (atto) or 32k 4kB iops (as-ssd).

    Throughput is not saturated with 4kB iops and the drives are different enough in other benchmarks.

    Is it a limitation of the usb/uasp protocol or the bridge chip, or something else?
  • avbohemen - Thursday, January 23, 2020 - link

    Sorry, I mean crystaldiskmark instead of as-ssd.
  • Soulkeeper - Thursday, January 23, 2020 - link

    The crucial looked like the winner untill I saw the Performance Consistency results. Horrible.
    Otherwise most the benchmark results, outside of this, seem very close for all the drives to me.
  • ganeshts - Friday, January 24, 2020 - link

    Exactly! And, dare I say, for most casual users, the Crucial drive actual works out well. It is only power users and tech-savvy folks who expect to 'torture' their external drives that need to watch out :) Unlike other review sites [ and I don't want to name any ;) ], our aim is to give the complete picture so that readers can make an informed purchase decision.

    To be honest, if I were to purchase a portable SSD for occasional periodic backups (say, 10 - 20 GB of data at a time), the X8 is actually a good candidate because of the pricing alone.
  • dcroteau - Thursday, January 23, 2020 - link

    What kind of fake data is that?
    An NVMe drive at 19 degree Celsius? Less than room temperature?

    They run notoriously hot and wouldn't be below 30C in any circumstances. They can go as high as 70C without a proper heat sink.

    Even with proper cooling, they will never be below room temp. 19C is very frisky for a room temperature.
  • ganeshts - Friday, January 24, 2020 - link

    It is winter here in CA and the room temperature in my lab is around 63F (as I rarely turn on the air-conditioning in the lab for winters - the benchmarking testbeds are operated remotely / headless).
  • Meteor2 - Saturday, January 25, 2020 - link

    My heating never goes above 19C. Put a jumper on and save the planet.
  • regsEx - Thursday, January 23, 2020 - link

    USB 3.2 Gen 2 is just rebranded USB 3.1. Actual USB 3.2 is Gen 2x2.
  • Tomatotech - Friday, January 24, 2020 - link

    I hope you understood that as I didn’t at all.

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