USB 3.2 Gen 2x2 State of the Ecosystem Review: Where Does 20Gbps USB Stand in 2020?
by Ganesh T S on October 5, 2020 10:30 AM EST- Posted in
- Storage
- SSDs
- Western Digital
- SanDisk
- ASMedia
- USB 3.2 Gen 2x2
Synthetic Benchmarks - ATTO and CrystalDiskMark
Western Digital claims claims read and write speeds of up to 2000 MBps for both the P50 and the Extreme PRO Portable SSD v2, and these are backed up by the ATTO benchmarks provided below. Unfortunately, these access traces are not very common in real-life scenarios.
| Drive Performance Benchmarks - ATTO |
 |
On the Haswell testbed, the Extreme PRO v2 hits 1.94 GBps writes, while the P50 manages 1.92 GBps. When connected using the eGFX enclosure to the Thunderbolt 3 port of the Hades Canyon NUC, the writes suffer a significant drop to the 1.4 - 1.5 GBps range, while the drop in the reads is not as drastic - ending up around 1.8 GBps for both of the drives.
CrystalDiskMark, despite being a canned benchmark, provides a better estimate of the performance range with a selected set of numbers. As evident from the screenshot below, the performance can dip to as low as 33 MBps for low-queue depth 4K random reads.
| Drive Performance Benchmarks - CrystalDiskMark |
 |
The sequential reads and writes are more useful from a direct-attached storage viewpoint. Here, we see around 2080 MBps for the Extreme PRO v2, and 2045 MBps for the WD_BLACK P50 as the best-case performance using the Haswell testbed.
Facebook
Twitter
RSS
81 Comments
View All Comments
six_tymes - Monday, October 5, 2020 - link
spot on. thank you for posting truths.vol.2 - Monday, October 5, 2020 - link
When I read it, it sounded like the issue was with USB 3.X devices operating on a USB4.0 chipset. My assumption, and I don't think it was explicitly addressed, is that USB4.0 would be "full speed" per it's own specs. Of course, it wasn't explicitly addressed (from what I took away from this), so I phrased my comment as a question; "So wait for USB4 devices then?"repoman27 - Monday, October 5, 2020 - link
You’re reading is pretty much on the money, but the answer to your question is a bit trickier.The first USB4 hosts to hit the market will (probably) be Intel Tiger Lake based products which have integrated Thunderbolt 4 and support USB4 40Gbps. The USB4 spec requires backwards compatibility with USB 3.2, including both the Gen 1 (5Gbps) and Gen 2 (10Gbps) PHYs. It does not, however, require USB3 dual-lane operation (Gen 2x2, 20Gbps), and Intel has not included this optional feature in the controller integrated into Tiger Lake CPUs.
If Intel doesn’t have any plans for integrated USB 3.2 20Gbps, I fail to see how it becomes widespread, unless Apple and AMD both embrace it in their future chipsets. On the other hand, USB 3.2 devices are probably always going to be cheaper than Thunderbolt or USB4 gear. Paying the premium for a USB 3.2 20Gbps device today is somewhat questionable, unless you have a capable host or the performance difference compared to other products when connected to a 10Gbps port is worth it to you.
magreen - Monday, October 5, 2020 - link
Why will USB3.2 20Gbps devices always be cheaper than USB43 gear? It seems likely USB3.2 20 Gbps will be a niche product and without being produced in high volume, street price won't come down. USB4 might be initially expensive, but volume production and competition may bring street prices down to what we see today for USB3.2 Gen 1 5Gbps devices.repoman27 - Monday, October 5, 2020 - link
Because USB4 is essentially Thunderbolt, but even more complicated. It will always take way more silicon and way more power than USB3 on the same node. Thus it’s never going to be as cheap. Economies of scale can’t solve everything.vol.2 - Thursday, October 8, 2020 - link
Sounds about right. I don't have a sudden need for USB 3.2 dual lane. It seems like the best case for more parties to forgo support for it altogether and push USB 4.0. On a related note, USB 3.X has always been very buggy and unstable/unreliable for me, so hopefully 4.X fixes some of that.Meteor2 - Monday, October 26, 2020 - link
Not if you plug a USB4-20Gbps or a USB4-40Gbps SSD into them.YB1064 - Tuesday, October 6, 2020 - link
Why is the ASM2364 winning in every scenario compared to Thunderbolt, if TB offers higher bandwidth? Am I reading this incorrectly?WTF is this godawful nomenclature dumpster fire??? The idiots on the USB standards committee need to be flogged with extreme prejudice.
repoman27 - Tuesday, October 6, 2020 - link
The ASMedia ASM2364 is the PCIe NVMe to USB3 20Gbps bridge chip used by the devices being tested for this review.The ASMedia ASM3242 is the USB3 20Gbps host controller that was used for testing these USB3 20Gbps drives.
The Intel JHL6540 is a Thunderbolt controller which includes an integrated USB3 10Gbps host controller for interoperability with USB3 devices. This was used to test these USB3 drives while connected to a USB3 10Gbps host. The ASM3242 is winning because it supports twice the USB3 signaling rate as the JHL6540.
When connected to a Thunderbolt 3 device, the JHL6540 supports up to 40 Gbit/s. In some of the tests, the ASM3242 card was actually plugged into a Thunderbolt 3 enclosure and connected to the host PC via the JHL6540.
Googer - Tuesday, October 6, 2020 - link
It's kind of sad to think that USB is now faster than SATA. Will there ever be a SATA 4 for SSD and future bulk storage technologies?