Question about M3 Max I/O throughput on USB-4/C.

[akdj]

I have the M3 Max and previously the M1 Max. I understand the last two models were capped at 3.2 Gen1 or 2, whichever was capped at 10Gb/s transfer rate.
Has this been changed in M3 or is there a way to use Thunderbolt’s 40Gb/s I/O to get 20Gb/s USB-C 3.3 Gen 2x2?

I couldn’t find any que about this yet

It’s kinda weird the big companies (SanDisk, Lexus, Samaung) are making 2x2/20Gb/s but not full support for the 40Gb/s I/O of Thunderbolt. And the companies who are - are unheard of and cost $100-$150 for the Thunderbolt enclosure, apparently with a built in controller to make the speeds so much faster (2500-3000Mb/s)

Why is Apple crippling the speeds of the very well advertised Thunderbolt and USB 4 capabilities now but cutting bandwidth speeds in half?

tIA
j

 

[Pressure]

Macs don't support USB3.2 (2 x 10Gbps). Apple support TB3/4 and USB4, which is vastly superior.

Thunderbolt 3 / 4 doesn't allow the full 40Gbps for data because of the specifications, so for best performance you would need a 2nd generation USB4 NVMe enclosure which would give you up to 3.8GB/s.

The reason is simply because of price. Thunderbolt 3 and 4 requires validation from Intel and USB4 is still more expensive to implement relative to USB3.

You should get something like the Maiwo K1695 USB4 NVMe enclosure (got mine for $54), HyperDrive Next USB4 NVMe enclosure, ZikeDrive USB4 NVMe SSD Enclosure Z666 or Satechi USB4 NVMe SSD Pro Enclosure.

Avoid DRAM-less SSDs despite them being dirt cheap, it will hurt sustained performance once it runs out of SLC or the drive is getting over 50% full.

Look for Samsung 980 / 990 Pro, Sabrent Rocket 4 Plus or WD_Black SN850X.

 

[theorist9]

For good I/O performance, you could get an external TB SSD enclosure and put in a high-performance SSD. Here's an example with an Acacis TB34 enclosure holding a 2 TB WD SN850X, attached to an M1 Max. The poster gets peak sequential R/W of ≈3 GB/s.

https://forums.macrumors.com/threads/thunderbolt-4-nvme-m-2-external-storage-read-write-speeds.2340127/page-9?post=32073949#post-32073949

Thouhg @Pressure is saying you can get even higher data transfer speeds with a USB4 case:

Thunderbolt 3 / 4 doesn't allow the full 40Gbps for data because of the specifications, so for best performance you would need a 2nd generation USB4 NVMe enclosure which would give you up to 3.8GB/s.

It's interesting that the theoretical data transfer speed is higher with USB4 than TB 3/4. But have you seen any independent measurements to confirm this translates into an actual improvement in performance--e.g. an Amorphous result showing ≈3.8 GB/s?

For instance, this reviewer on HyperDrives's site reported ≈3 GB/s with a 2 TB SN850X in HyperDrive's USB4 enclosure, when attached to an M2 Max, which is essentially the same figure reported above for an SN850X in a TB 3/4 case.

HyperDrive Next USB4 NVMe SSD Enclosure

Introducing the world’s fastest 40Gbps USB4 SSD Enclosure. The HyperDrive Next USB4 NVMe SSD Enclosure unlocks increased productivity by working directly from your SSD. Experience lightning-fast 40Gbps transfer speeds and seamless compatibility with M.2 NVMe SSDs. The easy snap-in installation...

www.hypershop.com

For even faster performance, you could buy a pair of TB3/4 SSD enclosures, put an SSD in each, and configure them in RAID 0. That would allow you to make use of 2 x TB ports, and give you peak sequential R/W of ≈6 GB/s:

https://forums.macrumors.com/threads/thunderbolt-4-nvme-m-2-external-storage-read-write-speeds.2340127/page-8?post=32028925#post-32028925

But now I'm wondering if, extrapolating from what @Pressure suggested, you could get even faster performance if you configured 2 x USB4 enclosures in RAID 0.

Or if you want a professional dual-TB RAID solution, and are willing to pay a lot for it, there's this from Iodyne: https://iodyne.com/specs/

 

[Pressure]

For good I/O performance, you could get an external TB SSD enclosure and put in a high-performance SSD. Here's an example with an Acacis TB34 enclosure holding a 2 TB WD SN850X, attached to an M1 Max. The poster gets peak sequential R/W of ≈3 GB/s.

https://forums.macrumors.com/threads/thunderbolt-4-nvme-m-2-external-storage-read-write-speeds.2340127/page-9?post=32073949#post-32073949

Thouhg @Pressure is saying you can get even higher data transfer speeds with a USB4 case:

It's interesting that the theoretical data transfer speed is higher with USB4 than TB 3/4. But have you seen any independent measurements to confirm this translates into an actual improvement in performance--e.g. an Amorphous result showing ≈3.8 GB/s?

For instance, this reviewer on HyperDrives's site reported ≈3 GB/s with a 2 TB SN850X in HyperDrive's USB4 enclosure, when attached to an M2 Max, which is essentially the same figure reported above for an SN850X in a TB 3/4 case.

Sure, just look at the specifications for Thunderbolt 3 and 4. Data is limited to 32Gbps bandwidth.

USB4 doesn't have that "limitation" in place.

Using the Maiwo K1695 USB4 NVMe enclosure I can hit the maximum for my old Samsung 970 EVO Plus which is around 3.4GB/s in AmorphousDiskMark. I'll grab a Samsung 990 Pro soon to test that.

 

[theorist9]

Sure, just look at the specifications for Thunderbolt 3 and 4. Data is limited to 32Gbps bandwidth.

USB4 doesn't have that "limitation" in place.

Using the Maiwo K1695 USB4 NVMe enclosure I can hit the maximum for my old Samsung 970 EVO Plus which is around 3.4GB/s in AmorphousDiskMark. I'll grab a Samsung 990 Pro soon to test that.

I'll look forward to hearing what you get with your 990 Pro.

Note that the stated bandwidth specs for TB and USB aren't quite comparable. It's more like 38-39 Gb/s vs. 32 Gb/s, rather than 40 Gb/s vs. 32 Gb/s:

As you may know, transmision schemes typically add dummy bits to offset DC bias. USB4 Gen 3X2 (which is the one that provides 40 Gb/s) uses 128b/132b encoding, which provides 4 dummy bits for 128 bits of data. Because USB4's 40 Gb/s includes that overhead, the actual bandwidth left for data is 40 x 128/132 = 38.8 Gb/s. Further, if they use Reed-Solomon forward error correction, that can reduce it to ~ 38 Gb/s.

Essentially, all standards except TB (including USB, SATA, DP, and HDMI) make their data bandwidth look higher than it really is by quoting the pre-encoding bandwidth, i.e., by including the dummy bits.

By contrast, Intel is more honest with its bandwidth specs. Their 40 Gb/s total bandwidth, and 32 Gb/s data bandwidth, are for data alone--they don't include overhead.

 

[Pressure]

I'll look forward to hearing what you get with your 990 Pro.

Note that the stated bandwidth specs for TB and USB aren't quite comparable. It's more like 38-39 Gb/s vs. 32 Gb/s, rather than 40 Gb/s vs. 32 Gb/s:

As you may know, transmision schemes typically add dummy bits to offset DC bias. USB4 Gen 3X2 (which is the one that provides 40 Gb/s) uses 128b/132b encoding, which provides 4 dummy bits for 128 bits of data. Because USB4's 40 Gb/s includes that overhead, the actual bandwidth left for data is 40 x 128/132 = 38.8 Gb/s. Further, if they use Reed-Solomon forward error correction, that can reduce it to ~ 38 Gb/s.

Essentially, all standards except TB (including USB, SATA, DP, and HDMI) make their data bandwidth look higher than it really is by quoting the pre-encoding bandwidth, i.e., by including the dummy bits.

By contrast, Intel is more honest with its bandwidth specs. Their 40 Gb/s total bandwidth, and 32 Gb/s data bandwidth, are for data alone--they don't include overhead.

I'm aware of overhead 👍🏼

 

[theorist9]

I'm aware of overhead 👍🏼

Sure, I figured you were. That's why I said "as you may know...". But were you aware of the fact that USB includes it in their spec but TB doesn't? I figured since you were comparing them by using 40 Gbps vs. 32 Gbps, you might not have been. That's something I didn't know until user @joevt explained it to me.

 

[akdj]

Thanks for the info

I'm aware of the TB enclosures and Sammy 990 Pros - OWC's TB drives, etc - but this round (M3) of MBPs - at least the Max, which I replaced the Max M1 with - is advertising their controllers differently. My M1 Max was Thunderbolt/USB 4 where the M3 says specifically in the description back of the box - Three Thunderbolt 4 Ports (USB-C) ports, HDMI, SDXC, etc.

Essentially implying the M3 has both TB and USB 4 (not 3 and 4)

SO if the USB-4 data is faster, where's the USB-4 controllers and enclosures? Will they work from the port or need to be externally powered to get to the speeds in discussion?

I just got the OWC Go Dock and picked up the T9 4TB from Samsung on a great sale and it's doing fine speed wise, doesn't bench like my internal but I can certainly offload big files fast and no interruptions using it as my bank of effects (audio/video/graphics) to/from - feels as though its internal - but I'm sure the Thunderbolt enclosures with the controllers are sweet. I wouldn't need to run 'em in RAID though - 2-3Gb/s is phenomenal.

Again, thanks - and did any one else noticed the different wording in Apple's descriptor this time on the M3s - instead of using Thunderbolt/USB-4 it's saying Thunderbolt 4 and USB?

J

 

[theorist9]

Thanks for the info

I'm aware of the TB enclosures and Sammy 990 Pros - OWC's TB drives, etc - but this round (M3) of MBPs - at least the Max, which I replaced the Max M1 with - is advertising their controllers differently. My M1 Max was Thunderbolt/USB 4 where the M3 says specifically in the description back of the box - Three Thunderbolt 4 Ports (USB-C) ports, HDMI, SDXC, etc.

Essentially implying the M3 has both TB and USB 4 (not 3 and 4)

SO if the USB-4 data is faster, where's the USB-4 controllers and enclosures? Will they work from the port or need to be externally powered to get to the speeds in discussion?

I just got the OWC Go Dock and picked up the T9 4TB from Samsung on a great sale and it's doing fine speed wise, doesn't bench like my internal but I can certainly offload big files fast and no interruptions using it as my bank of effects (audio/video/graphics) to/from - feels as though its internal - but I'm sure the Thunderbolt enclosures with the controllers are sweet. I wouldn't need to run 'em in RAID though - 2-3Gb/s is phenomenal.

Again, thanks - and did any one else noticed the different wording in Apple's descriptor this time on the M3s - instead of using Thunderbolt/USB-4 it's saying Thunderbolt 4 and USB?

J

According to Apple's tech specs, both the M1 Max and M3 Max are 3 x TB 4 with USB 4 support. So there's no difference in that respect between the two:

The wording "Thunderbolt/USB-4" is used when the computer doesn't meet the TB 4 standards, which requre it to (among other things) support 2 x 4k external displays. That's why the Base-M Mini is able to list itself as TB 4 (it supports two externals)

...while the Base-M MacBook Pro (and Air and iMac) cannot; they all have to drive their internal displays, so they can only drive one external.

The TB 3 standard has the same max speed as TB 4, but looser requirements. From: