When USB 4 (throughput) isn't quite claimed...in Mac-land

Perhaps this is down to my (mis)interpretation of USB 3.2 and USB 4 host port spec's, or maybe not:

A little tale about my Samsung T9 external SSD drive. This supports a claimed 2000 Mbytes/sec on sequential reads and sequential writes aren't too far behind, using a USB 3.2 Gen 2x2 interface and utilising the NVMe protocol.

As a couple of Macs we have here are running Firewire 4 ports with "support for USB 4 (up to 40Gb/s)" - I thought 'Great, should be able to get the full ~2000 or so Mbytes a second transfer speed'.....

Turns out errr no not really!

It's more like precisely half that on any MAC I've tested with Firewire 4 / USB 4 (up to 40 Gb/s) ports - getting just over 1000 Mbytes/sec on sequential reads. So Apple's Firewire 4 port is actually running at USB 3.2 Gen 2 speed (10 Gbps) only rather than claimed USB 4 = older USB 3.2 Gen 2x2 (20 Gbps). I tested with both AmorphousDiskMark (the Mac equivalent of CrystalDiskMark for PCs) as well as Samsung's own Magician software. Results pretty much matched.

Plugged into a ThinkPad with USB 4 ports (2 x USB-C). Same drive when tested using CrystalDiskMark (or Samsung Magician) pretty much gets full beans - getting over 2000 Mbyte/sec on sequential reads.

Is Apple telling a little white lie when it says its Thunderbolt 4 ports have support for USB 4 (up to 40Gb/s)" or is it because the drive technically 'only' supports USB 3.2 Gen 2x2 (20 Gbps)?

The latter doesn't make sense to me, as a USB 4 port on the ThinkPad get the full throughput.

I'm puzzled.

Edited by Pheasant (Sat 09-Nov-24 16:09:36)

In reply to a post by Pheasant:

"support for USB 4 (up to 40Gb/s)"

Maybe I'm cynical, but I've always taken "supports" (or "compatible with" etc) as meaning no more than "it will work with it", and that anything above what it did before is to be viewed as a bonus.

I'm much happier if I see the word "meets".

And then we have the dreaded words "up to"...

USB 4 @ 'up to' 40 Gbps: I'd be pretty happy to settle for USB 4 @ 20 Gbps 😎...but a low water mark of 10 Gbps is just a bit insulting. By golly that's positively 2013-era speeds!

Maybe USB 4 speeds will improve/get closer to their claims with Firewire 5 on the newest M4-based machines.

I'm going to have a grumble to Apple Support about it. At the very least it will make me feel better to vent. 😅

In reply to a post by Pheasant:

I'm going to have a grumble to Apple Support about it. At the very least it will make me feel better to vent. 😅

Sounds like latest Apple software, probably not been tested with a 3.2 2x2 (20 Gbps) device. I think the iPhone 15 Pro & 16 Pro’s support 3.2 (10 Gbps) so that will have been tested…

Good the Thinkpad showed the Samsung hardware working!

Yeah have checked this drive against M1, M2 and an M3 boxes - in normal, Max and Ultra guises. Desktop and laptop.

So it would seem it’s a failure across Thunderbolt 3 and 4 generations and chipsets - and not an isolated firmware glitch…unless it’s simply down to Apple’s Thunderbolt 3 or 4 restrictions / implementations, which would just be weird considering hardware should easily be good for 20 Gbps in USB 4.

Apple have openly claimed ‘up to’ 40 Gpbs for USB 4 on both generations of Thunderbolt on all these boxes from 2020….

No issues with pure Thunderbolt ; have been running an Atto 3252 25 GbE Ethernet network adapter and it’s not missed a beat all the way from Monterey to Sequoia on two different boxes.w

Maybe Apple just won’t play nice with Samsung! 😂

Hmmm to rule out a chipset incompatibility; think I’ll also try an OWC Express 1M2 USB 4 enclosure and see if that is any better. They do just an empty enclosure, so can just fit any M.2 NVmE SSD inside.

OWC make nice gear, having used their docking stations snd other bits and bobs over the years.

In reply to a post by Pheasant:

OWC make nice gear, having used their docking stations snd other bits and bobs over the years.

Good thinking, OWC are the ‘bees knees’ in Mac accessories.

👍. Yep it’s good gear. With the time difference last night, I must’ve managed to get the last shipment on Saturday from Woodstock Illinois: FedEx are on the way along with a couple of other bits to cover the courier charge.

Will see what Apple have to say about the Samsung drive too.

Updates coming later this week.

The enclosure from OWC arrived this morning (that was quick!) and so set about installing the Samsung NVMe stick inside.

It's a very nice enclosure; seems like it's made of billet, or at least hewn or carved from a single piece of alloy. Integral heat sink pads work well, as the fins on the case are warm to touch when the drive is working hard.

Over to performance. Happy to report that this Samsung 990 Pro drive and OWC enclosure combo is delivering the "full beans" on Apple hardware. Basically double the throughput on writes and reads from the same sized T9. This equates to a 'proper' 40 Gbps USB 4 connection on either the Thunderbolt 4 ports (with USB 4 support) on the Macs or USB 4 ports on ThinkPad.

A little tweak (change default disk removal policy is "Quick removal" to "Better performance") was required on Intel/Windows 11 to get the full performance, especially writes. Which went up by a factor of around 8 from the default!

So Apple weren't telling white lies. Just proves that as long as you put a Samsung SSD in the right box it will write well 🤣

In reply to a post by Pheasant:

Just proves that as long as you put a Samsung SSD in the right box it will write well 🤣

LOL, Apple remains insanely picky about accessories... something USB (any version) was supposed to correct. Sigh.

At the very least there’s clearly something going on with Apple’s support for USB 3.2 Gen 2x2 under Thunderbolt, at least with that Samsung T9 drive. I could probably spend the best part of an evening googling it. Might even be a limitation within the Thunderbolt (3 and 4) implementation itself that I’m not aware of.

To be fair to Apple, I’ve proven that with an accessory labeled USB 4 it it passing data at 40 Gbps, at least with Thunderbolt 4 equipped machines. I haven’t checked with earlier Thunderbolt 3 only machines.

I don’t think I can be bothered now to chase up with 🍏 why the T9 drive only transfers at 10 Gbps on USB 4. Their response will be quite predictable.

I can test later on with some new Thunderbolt 5 equipped Apple hardware to see if USB 3.2 Gen 2x2 throughout has improved, from Thunderbolt 3 and 4, gets the full 20 Gbps, but my expectations are low.

Will see.

In reply to a post by Pheasant:

At the very least there’s clearly something going on with Apple’s support for USB 3.2 Gen 2x2 under Thunderbolt, at least with that Samsung T9 drive. I could probably spend the best part of an evening googling it. Might even be a limitation within the Thunderbolt (3 and 4) implementation itself that I’m not aware of.

Fascinating as the iPhone 15 Pro/ProMax, and the 16 Pro/ProMax claim to support 3.2 Gen 2x2, whereas the 15/Plus and 16/Plus only support USB 2 protocol over the C connector. I think the new iPad Mini 7 is the same; but the iPad Pro models with M1 and later are Thunderbolt 4/USB4

To be fair to Apple, I’ve proven that with an accessory labeled USB 4 it it passing data at 40 Gbps, at least with Thunderbolt 4 equipped machines. I haven’t checked with earlier Thunderbolt 3 only machines.

Good to know it works.

I don’t think I can be bothered now to chase up with 🍏 why the T9 drive only transfers at 10 Gbps on USB 4. Their response will be quite predictable.

Agreed.

I can test later on with some new Thunderbolt 5 equipped Apple hardware to see if USB 3.2 Gen 2x2 throughout has improved, from Thunderbolt 3 and 4, gets the full 20 Gbps, but my expectations are low.

I see PCPro magazine's Jon Honeyball was discussing a Thunderbolt 5 cable in their weekly podcast last week. Insanly capable speeds.

In reply to a post by jchamier:

I see PCPro magazine's Jon Honeyball was discussing a Thunderbolt 5 cable in their weekly podcast last week. Insanly capable speeds.

Along with the OWC drive above, I ordered a couple of OWC's own-brand Thunderbolt 5 cables. In theory one could connect two M4 Pro / Max machines together and get bidirectional 80 Gbps with IP over Thunderbolt between them 😂

I believe TB5 will run up to 120 Gbps unidirectional.

Edited by Pheasant (Thu 14-Nov-24 22:10:05)

You keep saying FireWire, I assume you mean Thunderbolt 😉

Apple don’t claim to have USB 3.2 Gen 2x2 support:

https://support.apple.com/en-us/111835

I do. My bad. Apologies.

My brain often still thinks in FireWire terms. Thunderbolt. Thunderbolt. Thunderbolt. Is that like Bettlejuice? 🤣

Apple claim that the new M4 Minis have USB 4 ports. USB4 is mandated to be compatible with USB 3.2 Gen. 2.

But I think you are correct that there is no claimed support on earlier models.

They have claimed USB 4 (up to 40 Gbps) with every Apple Silicon generation that I'm aware of.

You are correct that earlier boxes (M1 and M2) were additionally listed/noted as supporting "USB 3.1 Gen 2 (up to 10 Gbps)" - irrespective of whether they had Thunderbolt 3 or Thunderbolt 4 ports.

However I also tested on an M3 Max box which in the Apple spec. simply say "...USB 4 (up to 40 Gbps)". There is no longer any separate mention by Apple in the spec for these machines for any USB 3.x support whatsoever. Ditto for the latest M4 boxes.

Edited by Pheasant (Fri 15-Nov-24 14:19:50)

Ah, then they are non-compliant iwith the USB specifications.

In reply to a post by Pheasant:

They have claimed USB 4 (up to 40 Gbps) with every Apple Silicon generation that I'm aware of.

M series processors, not the A series. The M series are USB 4 / Thunderbolt.

The A series with lightning are only USB 2, but the A series with Pro (15 Pro/Pro Max etc) with USB-C ports are USB 3 (10 Gbps), viz:
https://support.apple.com/en-us/111829

10Gbps seems to be USB 3.2 Gen 2 (aka Gen 2x1) in the insane naming of the USB-IF committee. (Formerly known as 3.1 Gen 2… )

USB 4 has similar stupid naming, until I read Wikipedia’s article, I didn’t realise USB 4 was based on Thunderbolt 3 design/signalling.

Indeed squire. Not referring to the telephonic instruments.

Apple Silicon being the moniker of M-series desktop and laptop beasts since they parted ways with Intel. iPads and iPhones as you’re all too well aware have always been “Apple Silicon” since inception.

USB naming, etc just leaves me confused 😵‍💫

In reply to a post by Pheasant:

Indeed squire. Not referring to the telephonic instruments.

Apple Silicon being the moniker of M-series desktop and laptop beasts since they parted ways with Intel. iPads and iPhones as you’re all too well aware have always been “Apple Silicon” since inception.

They use the "Apple Silicon" any time Johnny Sriji is on screen for all the products

USB naming, etc just leaves me confused 😵‍💫

Someone needs to beat the USB-IF around the head with a wet kipper, skipper.

I guess to be a someone in Apple you need to be a Johny or a Jony 😅

In reply to a post by Pheasant:

I guess to be a someone in Apple you need to be a Johny or a Jony 😅

LOL.. and I obviously can't spell.

https://en.wikipedia.org/wiki/Johny_Srouji

No fear, I’m not the grammar and spelling police👮…today anyway 😉😂

Edit: my OP is full of complete howlers with FireWire splattered in place of Thunderbolt. Sadly I didn’t even clock it when I was writing it. How bad is that!!

Edited by Pheasant (Sat 16-Nov-24 11:14:41)

In reply to a post by TinyMongomery:

Ah, then they are non-compliant iwith the USB specifications.

...yes as it stands, from what I've (very limited) tested. They're certainly not compliant with USB 3.2 Gen 2x2 device(s) - or at least don't pass the full line rate, just 10 Gbps.

However if the device says its USB 4 then they appear to be compliant (pass full rate) @ 40 Gbps.

I'm not going to waste time asking Apple 'why' this is. Doubtless they will just point me to the spec. page of the earlier machines which says USB 4 (up to 40 Gb/s) and USB 3.1 Gen 2 (up to 10 Gb/s).. and the latter takes precedence in Apple-universe.