The SanDisk Extreme PRO Portable SSD released in 2019 has been one of the top performers in the external flash storage market segment. Putting a high-end WD Black SN750-class M.2 PCIe 3.0 x4 NVMe SSD behind an ASMedia ASM2362 bridge helped it deliver speeds of up to 1050 MBps when used with USB 3.2 Gen 2 ports. One of the key differentiators was its performance consistency under heavy sequential writes, with no SLC caching effects (write speed cliff) or thermal throttling. Coupled with its handy industrial design (in particular, the carabiner loop integrated into an easy-to-carry casing), it has been on top of our list of recommended USB 3.2 Gen 2 external SSDs since the beginning of this year. Along with the 2019 PRO, SanDisk also offered the lower-priced 2018 SanDisk Extreme - a SATA SSD behind a USB 3.2 Gen 1 bridge. Despite thermal throttling under stress, the performance and price made the 2018 Extreme Portable SSD an attractive option for casual users.

Today, Western Digital is upgrading both the SanDisk Extreme and the Extreme PRO Portable SSDs models with a v2 suffix - Accompanying that is an approximate doubling of the peak bandwidth numbers for both models. In short, the SanDisk Extreme Portable SSD v2 is now a USB 3.2 Gen 2 device with speeds of up to 1050 MBps. The SanDisk Extreme PRO Portable SSD v2 is a USB 3.2 Gen 2x2 device with speeds of up to 2000 MBps.

A detailed review of the 1TB model of the SanDisk Extreme Portable SSD v2 (along with the recently introduced WD My Passport SSD (2020) 1TB version) is available here. A DRAM-less SN550-class NVMe SSD is used behind an ASMedia bridge, allowing for lower power consumption and a relaxed thermal design compared to the 2019 Extreme PRO Portable SSD (which also claimed read/write speeds of up to 1050 MBps).

The Extreme PRO Portable SSD v2 uses the WD Black SN730E SSD, which is essentially the OEM version of the SN750, but upgraded to 96L BiCS 4 3D NAND flash, and has firmware tweaked for use with external drives. The PCIe 3.0 x4 NVMe interface allows the Extreme PRO Portable SSD v2 to support read/write speeds of up to 2000 MBps. The forged aluminum heat sink used in the 2019 SanDisk Extreme PRO is carried over to prevent thermal throttling. The SSD also has a 2m drop protection. New to the v2 SSDs is official compatibility with a range of USB Type-C smartphones.

The USB 3.2 Gen 2x2 port in the PRO v2 is enabled by the ASMedia ASM2364 bridge chip. The SanDisk Extreme PRO Portable SSD v2 is not the first USB 3.2 Gen 2x2 drive from the Western Digital stable. Late last year, WD had started selling the WD_BLACK P50 with similar advertised speeds. Targeting the gaming market, the WD_BLACK P50 had a unique industrial design and utilized a SN750E internal SSD (64L BiCS 3 3D NAND flash) - a version of the SN750 with tweaked firmware.

Despite the appearance of USB 3.2 Gen 2x2 ports in certain high-end motherboards, and the announcement of several USB 3.2 Gen 2x2 PCIe cards, the uptake of this high-speed interface in the computing world has been limited. Announced cards (such as the GIGABYTE GC-USB 3.2 GEN2X2) are yet to become available in the retail market. In fact, only the WD_BLACK P50 and the Seagate Firecuda Gaming SSD appear to be USB 3.2 Gen 2x2 client devices from well-known manufacturers available for purchase today. They are now joined by the SanDisk Extreme PRO Portable SSD v2. Western Digital indicated that they expect increased adoption of USB 3.2 Gen 2x2 next year on the host side. Given that the Tiger Lake platform doesn't support USB 3.2 Gen 2x2, it is going to be interesting to watch how this plays out in the near future. We will have some additional comments on the state of this market segment and hands-on reviews of some USB 3.2 Gen 2x2 gear in the coming days.

Both of the drives being introduced today have an operating temperature range of 0 to 45C, and come with an IP55 ingress protection rating. The drives are also getting hardware encryption support, which brings them on par with the WD My Passport SSD as far as security is concerned. Western Digital also indicated that their confidence in BiCS 4 flash is allowing them to upgrade the warranty on the SanDisk Extreme model from the usual 3 years to 5 years. On the pricing front, the USB 3.2 Gen 2x2 Extreme PRO Portable SSD v2 is priced at $300 and $500 for the 1TB and 2TB versions. The Extreme Portable SSD v2 has a suggested retail price of $120, $200, and $355 for the 500GB, 1TB, and 2TB versions respectively.

Source: Western Digital

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  • repoman27 - Wednesday, September 30, 2020 - link

    "Given that the Tiger Lake platform doesn't support USB 3.2 Gen 2x2, it is going to be interesting to watch how this plays out in the near future."

    Glad to see that you caught that. I was pretty surprised when I saw the lack of USB3 dual-lane operation while perusing the Tiger Lake UP3 datasheet. I had really hoped that Thunderbolt 4 would support all of the headline features of both the USB 3.2 and USB4 specifications.
  • JfromImaginstuff - Wednesday, September 30, 2020 - link

    I didn't even know that there was such a standard as USB 3.2 Gen 2X2. Well there's always more to learn.
  • repoman27 - Wednesday, September 30, 2020 - link

    USB 3.x / SuperSpeed USB 5Gbps is Gen 1 signaling.
    USB 3.x / SuperSpeed USB 10Gbps is Gen 2 signaling.
    USB 3.2 / SuperSpeed USB 20Gbps is Gen 2 signaling plus dual-lane operation, a.k.a. Gen 2x2.
  • brutedawg - Wednesday, September 30, 2020 - link

    USB naming standards are such a mess, made shopping for a motherboard this past year an absolute pain with virtually every manufacturer inconsistently naming their I/Os.
  • Arsenica - Wednesday, September 30, 2020 - link

    If would be very simple if only they had made something like this:

    USB 3: 5Gbit/s - Type A connector (known as USB 3.2 Gen 1×1)
    USB 4: 10Gbit/s - Type C connector (known as USB 3.2 Gen 2×1)
    USB 5: 20Gbit/s - Type C connector (known as USB 3.2 Gen 2×2)
    USB 6: 40Gbit/s - Type C connector (known as USB 4 Gen 3×2)
  • repoman27 - Wednesday, September 30, 2020 - link

    I'm sure that with hindsight the USB-IF might have elected to do things differently. However, from their standpoint, it probably seemed easier to add a couple new signaling modes as optional features in point releases and not have to roll new licensing or maintain additional specifications and associated testing / compliance programs.

    Also, USB 3.1, which introduced the Gen 2 (10Gbps) PHY, was developed for Standard/Micro-A/B connectors and was finalized over a year prior to the Type-C Cable and Connector Specification. And USB4 hosts/devices only need to support Gen 2x2 (20Gbps) signaling, or up to Gen 2x1 (10Gbps) in USB3 mode.

    Optional features can be beneficial to manufacturers and consumers alike, but they make the specification version number an unreliable indicator of device capabilities. And to a certain degree, the differences between the USB 3.x variants really only matter in edge cases. For years now, nobody has complained that USB 2.0 encompasses devices that might be capable of low-speed (1.5 Mbit/s), full-speed (12 Mbit/s), or high-speed (480 Mbit/s) signaling, despite the fact that they are separated by orders of magnitude. As long as the signaling rate is appropriate for the device, nobody cares. PC host ports are pretty much the only place where you might want to pay attention to the signaling capabilities, but a 10Gbps device only operating at 5Gbps is unlikely to impact most real-world workflows.
  • ganeshts - Thursday, October 1, 2020 - link

    I am curious why you say 'a 10Gbps device only operating at 5Gbps is unlikely to impact most real-world workflows' ; For content creators on the go, for example, backing up work files from their desktop PC before venturing out to the field is a legitimate real-world workflow. A device operating at half the advertised speed is bound to double the waiting time of the user.

    I do agree that all the version numbers have been designed from the viewpoint of what manufacturers need to do / support to obtain certification - However, based on prior experience, USB-IF must have recognized that the version numbers are bound to be marketed directly to consumers. Reading more into the USB4 standard and its implementation in Tiger Lake, I am strongly convinced that it is shaping out to be a disaster in terms of consumers understanding its capabilities (akin to what has been happening with Type-C over the last few years).
  • repoman27 - Thursday, October 1, 2020 - link

    The only time you benefit from Gen 2 signaling is when your attached device is capable of throughput greater than 435 MB/s. That means multiple SATA drives in a hardware based striped RAID configuration or PCIe SSDs with a Gen 2 bridge. Although the theoretical max throughput for Gen 2 (~1050 MB/s) is more than double that of Gen 1, the real-world throughput difference is dependent on the capabilities of the storage media and the access pattern. Your benchmarks prove this out. Take any of the write benchmarks from the AnandTech DAS Suite and compare them to the same device plugged into a Gen 1 port.

    The time is money set switched to Thunderbolt eight years ago and haven't looked back. USB 3.2 Gen 2x2 is essentially nonexistent and it appears that Intel wants to keep it that way by moving everyone to USB4 / Thunderbolt 4 instead. There are very few device categories for which USB3 Gen 2 silicon exists, and even basic items such as hubs are still exceedingly rare in the marketplace.

    In many cases, USB3 is preferable to Thunderbolt because devices are considerably cheaper and will work just fine if you plug them into any USB port. But I think some users would trade the speed bump that comes with Gen 2 signaling simply to be able to use passive cables longer than 1m. The differences between USB 1.1, 2.0, and 3.0 were so great that they enabled entirely new use cases. What's the killer application for USB3 Gen 2 aside from "sometimes it's a bit quicker"?
  • repoman27 - Wednesday, September 30, 2020 - link

    Top tip: when it comes to USB 3.1 and 3.2 gear, ignore the number to the right of the decimal point, because the specification version number does not determine device signaling capabilities. Look instead at the part where it says 5/10/20Gbps, which all licensees are supposed to include in any marketing materials or packaging where the USB 3.1 or 3.2 version numbers are mentioned.

    Also, 20Gbps is only for USB 3.2 Type-C ports that support dual-lane operation, which currently requires a discrete controller and are as rare as hen’s teeth.
  • Jorgp2 - Wednesday, September 30, 2020 - link

    Fuck, USB is confusing.

    Intel states TG supports USB 4 Gen 2 x 2, which is the same speed as USB 3 Gen 2 x 2 but electrically incompatible.

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