The comparison is between a Mac with an Apple M series processor vs an Intel based Mac, using either a Thunderbolt 3 vs a USB4 external enclosure for the (unspecified) SSD.
The conclusion is that for the Intel Macs it does not make much of a difference, but for the M series there is a benefit from going USB4.
The article is very light on methodology or actual data.
This article talks about TB4 vs USB4 but that's a
red herring. This has nothing to do with USB4 and
Intel USB4 compliant controllers have the same problem.
The real reason Apple Silicon is faster is simple:
Intel Thunderbolt controllers are *external* and
bottlenecked on a PCIe 3.0 x4 link to the host,
while Apple Silicon *embeds* the controllers right
into the SoC, so there is no physical PCIe link
anywhere. They connect directly to the much faster
SoC fabric, so have no such bottleneck.
There's only a real issue with capacity if you're using USB4, so I don't see how it's a red herring. Also, I've just read that Thunderbolt 3 has a hard reservation of 18 Gbps for display port data, limiting other data to 22 Gbps, so comparing TB3 to TB4 in pci-e mode will have that caveat as well.
hector goes over this as well, but basically you've replaced all the lower (physical) layers of PCIe's networking stack. intel like to pretend that thunderbolt and USB4 just tunnel actual PCIe links unchanged (as if they're emulating everything down the PCIe lanes and PHYs), but they don't. PCIe over thunderbolt can run at whatever speed you please, limited only by the throughput of TB and the overhead of the remaining layers of the PCIe stack.
It's worse than that; if you use a USB4 enclosure with an Intel Mac (or, really, just about any computer that's more than a few years old), it'll run at 10Gbit/sec (because USB3 is the fallback point, not Thunderbolt 3), but if you use it it with ARM Mac it'll run at 40Gbit/sec. If you use a Thunderbolt 3 enclosure instead it'll run at 32Gbit/sec in both cases. All bets are off if Thunderbolt 4.
As always, USB, and associated standards like Thunderbolt, continue to be absolutely baffling. I think there had been the perception that USB4 would make all this a bit less confusing, but it very much hasn't.
Although in practice I find it pretty easy to pick out power-only UBC-C, USB-only USB-C, and Thunderbolt USB-C, by the build quality/thickness of the cable. What's aggravating is devices (cheap ones) which use the USB-C port but will only charge from an OG 500mA charger. I keep those chargers in rotation as a result, but they're useless for any other purpose.
Read 2692 MB/s
Write 1774 MB/s
Not exactly, as it actually mentions intel macs do not support USB4, so USB4 enclosures will fall back to USB3 which is slower than TB3. The article is no less confusing than the actual topic. So the actual advice is TB3 for intel macs, USB4 for apple silicon.
- it's almost impossible to tell a priori what the performance will be, since manufacturers don't document their chipsets properly
- a faster drive may be slower on an Intel Mac, due to falling back to USB3
While I would agree the article should link to more details, they are easy to find on the site. In fact, the author has written many benchmarking tools. Here are their tools related to disk and file system performance:
https://eclecticlight.co/dintch/
It is a fair bet, they used their own benchmark tools. You can read other articles on the site that describe their work.
That's because it's not a benchmark, it's an explanation.
It's certainly an article that uses the word 'may' several times in the text, yet not once in its title.
All those extra modes sound great on marketing slides, but the upshot is that consumers no longer know what they're getting when reading a spec sheet on Amazon. So you get articles like this purporting to say something about Apple products when almost certainly it's down to the lack of Intel Macs on a benchtop at whatever vendor packaged that drive.
[1] In the last nine years there have been four independently issued USB standards and IIRC another two for Thunderbolt before the USB4 convergence. That's just not a reasonable landscape for a vendor to "support" in any meaningful way. Stuff that is correct at design time is obsolete by the time it ships, and the industry makes up for the churn by just skipping testing with the "old" stuff.
With TB, you know exactly what are you getting. On the connector, there's a flash icon (meaning: thunderbolt) and a number (if > 3). That number says, which TB version it is.
Even with USB4, there's no convergence. USB4 made TB alternate mode optional. USB4 is no guarantee, that you can use TB.
The article is literally detailing a Thunderbolt device that behaves differently when plugged into different macs, precisely because of the ambiguity introduced by the USB4 modes.
"You know exactly what you are getting" is a story about a specification being unambiguously written. It doesn't say anything about what happens when you have dueling specs on the same port, which is the problem here.
So, you agree that the specification landscape is a soup of incompatible variants which make practical interoperability mostly a crap shoot for consumers. You just don't think that's a problem?
One related complication of sharing a physical standard is that all Thunderbolt 4 cables work for USB 4, but the reverse isn't true. Ideally that would not be the case, but people want their cheap USB cables.
that's absolutely not true at all - for example, cables can be either active or passive, which is not denoted on the cable. Many devices will not work over a passive cable, because it does not provide power.
It is not this. PCIe can be encapsulated over a Thunderbolt connection, but that is not what Thunderbolt is. Thunderbolt is Thunderbolt.
1. problems are mostly thermal for external devices, ie if you have an enclosure that is not good for dissipating heat, and the device consumes Watts of power... it is unlikely you will see sustained performance
2. Not all USBC interfaces are alike, and getting USB2, USB3, USB Super Speed or USBC performance will vary based on
a. the usb cable construction / performance spec,
b. the usb-c cable orientation in the socket (yes they are symmetric, but not physically sometimes),
c. the port you plug into,
d. the orientation of the usb-c cable in the socket.
If you are a person who desires more texture:
1. the real speed limit is how many lanes of PCI/CXL are extended to the controller on the USB bus, the controller on the device,
2. and the raw performance of the nand device, ie how many addressable bits are available per cycle &/or the amount of real-time recovery in LDPC that is successful in single pass ... ie optimization of throughput.