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 🤣