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
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.
The write workloads see the Extreme PRO v2 come out slightly better than the WD_BLACK P50 using the Haswell testbed. On the reads, we see the Hades Canyon / eGFX enclosure turning out to be better - this can be attributed in part to the capabilities of the testbed itself, rather than the PCIe tunneling chain. In any case, we don't see any significant gulf in the numbers between the different units as long as the observations are made within the USB SuperSpeed 10Gbps or USB SuperSpeed 20Gbps host configurations.We also instrumented our evaluation scheme for determining performance consistency.
Performance Consistency
Aspects influencing the performance consistency include SLC caching and thermal throttling / firmware caps on access rates to avoid overheating. This is important for power users, as the last thing that they want to see when copying over 100s of GB of data is the transfer rate going down to USB 2.0 speeds.
In addition to tracking the instantaneous read and write speeds of the DAS when processing the AnandTech DAS Suite, the temperature of the drive was also recorded at the beginning and end of the processing. In earlier reviews, we used to track the temperature all through. However, we have observed that SMART read-outs for the temperature in NVMe SSDs using bridge chips end up negatively affecting the actual transfer rates. To avoid this problem, we have restricted ourselves to recording the temperature at either end of the actual workloads set. The graphs below present the recorded data.
| Performance Consistency and Thermal Characteristics |
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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. There is no issue with thermal throttling - even in the fastest configuration, both the P50 and Extreme PRO v2 show an increase of less than 5C after the workload processing. The P50 seems to have slightly better thermal performance for this workload set.
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DanNeely - Monday, October 5, 2020 - link
Read the last page of the article. The USB maintainers have decided to make USB4 even more of a garbage fire of confusion than previous versions. USB4-20gb and USB-40gb ports are only required to support 10gb data rates for USB drives (and can count bandwidth to alternate data stream devices, ie parallel video out) toward the total.IMO it's past time to disband the current USB group, and create a new C(ompetant)SB organization to maintain future standards that bans anyone involved in the USB 3.x/4.x nomenclature from membership.
Spunjji - Monday, October 5, 2020 - link
I'm actually inclined to agree. It's gone way, way past being a joke at this stage.Kangal - Tuesday, October 6, 2020 - link
Well, we can always ditch USB3.1 / USB4 as consumers.Instead ask for USB-A (3.0) for legacy support, and then opt for USB-C (TB4) instead. Just say "hell no" to the USB-IF consortium and their broken standards.
Yet, that might be okay for now/per individual, but it's not gonna solve anything in the long run. And even worse, we can't actually do that because there is a lack of options in the market (ie You don't get to choose which ports your device has, you are stuck with whatever option they deem good for you). Tough times.
repoman27 - Monday, October 5, 2020 - link
Stop spreading FUD and read the specs, they're freely available for download. USB4 operates at 20Gbps (Gen 2x2) or 40Gbps (Gen 3x3) but it's a tunneling protocol, i.e. a *totally different* protocol than USB3. Backwards compatibility is mandatory and at least USB3 10Gbps (Gen 2x1) as well USB 2.0 signaling is required. USB 2.0, 3.2 and 4 involve different signaling and different protocols.USB4 supports tunneling of PCIe and DisplayPort packets in addition to native USB packets so that the total bandwidth can be flexibly and efficiently shared. Not bothering to understand this and instead spewing internet outrage helps no one.
repoman27 - Monday, October 5, 2020 - link
D'oh, that should have been "40Gbps (Gen 3x2)".ganeshts - Monday, October 5, 2020 - link
@repoman27's technical explanation is A-OK :) The move to tunnelling is definitely a big step for USB.However, @DanNeely's comment is also correct from a *consumer* viewpoint ; Would a regular non-tech savvy consumer care about tunnelling? If he sees USB4 20Gbps, would it be unfair for the person to expect his USB SuperSpeed 20Gbps device to work to its full potential in it?
All these problems could have been avoided if USB 3.2 Gen 2x2 capabilities were integrated into USB4 as mandatory.
repoman27 - Monday, October 5, 2020 - link
Oh, totally. But on the other hand, if Intel had just included USB 3.2 dual-lane operation in Tiger Lake / Thunderbolt 4, nobody would have realized it was optional, because it would have been supported everywhere one might expect it. I’m afraid that Intel intends to completely forego USB 3.2 dual-lane operation in favor of Thunderbolt.Kevin G - Monday, October 5, 2020 - link
It mainly boils down to USB 3.2 @ 20 Gbit not being the same implementation as USB 4 @ 20 GBit, a very year 2020 problem to have.There is still interoperability between the two but that knocks the speeds down to 10 Gbit. That is noticeable for things like storage doing transfers on fast SSDs etc. From a consumer stand point though, things will still work which I would rank as more important.
I will say that these issues lay with the USB consortium as they've created a mess of specifications that makes it difficult for things to work *as advertised*. Historically they also have needed to crackdown to lazy implementations and bad cables. Give that group a bit of teeth to enforce their spec and things would be far better for consumers today.
repoman27 - Monday, October 5, 2020 - link
Well, at the risk of beating a dead horse, nothing prevents a USB4 host/device from also supporting USB 3.2 20Gbps. It’s just that it’s optional, Intel didn’t include it in Tiger Lake, and I’m not aware of anything on their roadmap that will in the near future.You can choose to blame the USB-IF, Intel, or the fact that Intel pretty much runs the USB-IF. But at this point Intel hasn’t shown us any products containing USB 3.2 20Gbps IP, and without Intel on board, I’m not sure what kind of future that standard has.
Spunjji - Wednesday, October 14, 2020 - link
Makes sense. They've been artificially holding the standard back ever since they decided they'd rather push Thunderbolt over USB 3.