The emergence of 3D TLC flash has enabled a new class of budget-friendly bus-powered external SSDs. Flash memory has also seen a recent drop in prices, and this has made high-capacity drives affordable. Current external flash storage devices fall under one of four categories:

• Thumb drives with a direct flash to USB interface
• External SSDs implementing one of the following configurations:
  • SATA drive behind a USB bridge
  • NVMe drive behind a USB 3.1 Gen 2 bridge
  • NVMe drive behind a Thunderbolt controller

Today's review takes a look at two 2TB drives from Seagate (under the LaCie brand) and Western Digital. They belong to the second category in the above list, placing a SATA drive behind a USB 3.1 Gen 2 bridge.

Introduction and Platform Analysis

Thumb drives usually come with USB 2.0 or USB 3.0 interfaces, and are meant to plug in directly into the host port without an extra cable. Capacities have been steadily increasing, though very few high-end models boast of peak performance in the 300 - 400 MBps range. Most low-end and mid-range thumb drives have write speeds of the order of 20 - 80 MBps, and read speeds of the order of 100 - 150 MBps. Over the last few years, we have had vendors place a 2.5" SSD board behind a SATA - USB 3.0 bridge. These have now evolved into M.2 SATA SSDs behind a much smaller and more power-efficient SATA - USB 3.1 Gen 2 Type-C bridge. Such external SSDs now make up the bulk of the mid-range and high-end bus-powered external direct-attached storage devices. Consumers requiring very bus-powered external storage with very high performance are served by Thunderbolt 3 SSDs that are surprisingly affordable despite their performance profile. These SSDs put a M.2 PCIe NVMe SSD behind a Thunderbolt 3 controller and deliver performance equivalent to an internal PCIe 3.0 x4 M.2 NVMe drive (up to 3 GBps). Recently, we have seen PCIe 3.0 x2 NVMe SSDs behind a NVMe-USB 3.1 Gen 2 bridge that provide performance numbers of around 1 GBps.

The LaCie Portable SSD has the same internals as that of the Seagate Fast SSD that we had reviewed back in September 2018, while the WD My Passport SSD 2TB variant is similar to that of the SanDisk Extreme Portable SSD covered in the same review. However, the WD My Passport SSD 2TB variant uses a different firmware (in addition to the changed capacity) that enables hardware encryption compared to the one in the SanDisk Extreme Portable SSD.

Similar to the Seagate Fast SSD, the LaCie Portable SSD has a square form-factor and a traditional 2.5" SSD board inside. The 9mm x 79mm x 94mm device comes in at 82grams. Unlike the silver gray / black exterior of the Fast SSD, the LaCie Portable SSD sports a completely black exterior with a gold lining around the ridge.

Two 18in. cables - a Type-C to Type-C, and a Type-C to Type-A one are bundled. Value additions include two free months of the Adobe Creative Cloud Photography Plan, and a bundled Seagate Rescue data recovery service plan. The latter is not available with the Seagate Fast SSD. The internals are essentially the same as the Fast SSD - Toshiba BiCS 64-layer 3D TLC coupled with a re-branded Phison S10 controller behind an ASMedia ASM235CM bridge chip. The unit also has extensive thermal protection, similar to the Seagate Fast SSD.

The Western Digital My Passport SSD, on the other hand, has the same industrial design and package components as the 1TB Best Buy-exclusive variant we had reviewed in mid-2017. That version, despite sporting a USB 3.1 Gen 2 interface, was handicapped by the planar TLC-equipped SanDisk X400 inside. Western Digital has since updated the product line to use the WD Blue 3D NAND SSDs with 64-layer 3D TLC flash. The 2TB variant discussed in this review carries the WDBKVX0020PSL-WESN model number.

The My Passport SSD's gumstick form-factor (45mm x 90mm x 10mm) points to the use of a M.2 SSD inside. Instead of supplying two different cables with the unit, WD only provides a Type-C to Type-C cable along with a small Type-C to Type-A adapter. Despite the adapter's Type-C female interface, the included Type-C to Type-C cable can be plugged into it in only one orientation (indicated by a triangular mark on the adapter as the cable).

The drive comes pre-formatted in exFAT. It includes some software installers to enhance the utility of the product  - WD Discovery & Drive Utilities, WD Backup, and WD Security. The WD Backup software can be used to create scheduled backups of certain folders on the PC to the SSD. WD Security allows the setting of a password (up to 25 characters) that activates the hardware encryption features on the drive. The drive needs to be unlocked with the password upon system restart, or drive reconnect, or exit of the system from sleep mode.

The My Passport SSD is not as easy to take apart as the SanDisk Extreme Portable SSD. Evidence from a teardown video lends credence to the fact that the internal MILAN II M.2 SATA SSD is indeed a variant of the WD Blue 3D NAND SSD seen in the SanDisk Extreme Portable version. MILAN II is likely different from the retail variants of the WD Blue 3D NAND SSD in terms of firmware features such as self-encryption.

Drive Power Consumption - CrystalDiskMark Workloads

WD My Passport SSD 2TB (Alpine Ridge)LaCie Portable SSD 2TB (Alpine Ridge)LaCie Portable SSD 2TB (ASM 2142)WD My Passport SSD 2TB (ASM 2142)

When connected to the Alpine Ridge host, the WD My Passport SSD consumes less than 3.6W throughout the course of the workload set, and idles at around 1.3W. In the same setup, the LaCie Portable SSD behaves strangely, idling at 0.9W but having sporadic spikes of up to 5W. As mentioned multiple times in the preceding sections, the behavior of the LaCie Portable SSD with the Alpine Ridge host was not along expected lines. Moving on to the behavior with the ASM 2142, the WD SSD spends more time around the 3.6W mark, and even having a peak above 4W. The LaCie SSD has multiple peaks around 4.5W and even a couple in the 5.5W range, though idling power was as low as what was seen with the other host. These higher power numbers commensurate with the higher performance.

Coming to the business end of the review, the WD My Passport SSD and the LaCie Portable SSD both provide great performance, though some caveats apply. Prior to discussing those, we take a look at the pricing aspect.

The WD My Passport SSD is significantly cheaper than the LaCie Portable SSD. It also comes with hardware encryption support. However, the LaCie Portable SSD comes with some value additions such as a complimentary free month for the Adobe Creative Cloud All Apps plan and a three-year Seagate Rescue Data-Recovery Service plan. These value additions make the drive very attractive for content creators.

Neither SSD is perfect - the My Passport could do with a better thermal solution, as it ends up throttling under scenarios where the LaCie Portable SSD has no trouble. On the other hand, the LaCie Portable SSD seems to have compatibility issues with the Alpine Ridge host controller on Windows, with the write performance getting severely hampered. The LaCie Portable SSD performs like a champ with the ASMedia ASM 2142 host, though. For the average user, the WD My Passport SSD is able to deliver good performance with both host controllers.

As flash memory prices come down, it creates a chance for consumers to be able to purchase affordable high-capacity external SSDs. We fully expect to see QLC-based external drives hit the market soon, and that would become a value play for the manufacturer, rather than the consumer. As NVMe - USB bridge chips become more popular, it will create a high-end external SSD market, pushing out Thunderbolt 3 SSDs to the premium end. All things put together, 3D TLC flash memory strikes the right balance between endurance and cost. SATA SSDs (with 3D TLC flash) behind USB 3.1 Gen 2 bridges, like the WD My Passport SSD and the LaCie Portable SSD we reviewed here, hit the sweet spot in terms of price, performance, and capacity for the mass market.