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Souponastick270

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Mar 21, 2016
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Last year I set up my late 2012 iMac to boot and run off an external SSD via USB 3 using a Crucial MX500 1TB Sata in an enclosure. It's working great, no issues at all so I'm not complaining. The current chain looks like this:

iMac with USB 3 > USB 3 to USB C cable > USB C to SATA enclosure with MX500 inside

I'm now wondering if there is any performance left on the table, so I was thinking is it possible to make a boot drive on an M.2 NVMe drive in an enclosure and run it via Thunderbolt 1. My thinking is the chain would look like this:

iMac Thunderbolt 1 > Thunderbolt 1/2 cable > Apple Thunderbolt 2 to 3/USB C adaptor > USB C to M.2 NVMe enclosure with an M.2 SSD inside.

Anyone done this or have this set up at the moment ? Or am I thinking of this all wrong ? On the plus it would free up one of my USB ports not having the current boot drive taking up a slot.
 

Ledgem

macrumors 68020
Jan 18, 2008
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I don't think it will work as you're intending. From Apple's adapter support page:
This adapter is not compatible with USB-C ports that don't support Thunderbolt 3, such as USB-C hubs or the USB-C port on MacBook models from 2015 or later.

One possible work-around would be to get a Thunderbolt hub. This is what I have done to power a Thunderbolt 3 enclosure (in my case, a CalDigit TS3+ hub) with a M.2 NVME drive with my 2015 iMac (which has Thunderbolt 2 ports). The Thunderbolt hub does also have USB ports. If you're just looking to have accelerated USB speeds (or the ports), the CalDigit Elements Thunderbolt 4 hub might be a better choice.

As to whether you'd gain much... hard to say. I'm guessing your USB 3 ports are operating at 5 Gbps (625 MB/s) - you'll lose some speed to overhead, but that's already nearing the max speeds for your drive (according to Crucial's website, around 560 MB/s read and 510 MB/s write). Even if you jump up to Thunderbolt 1 speeds (10 Gbps, or 1250 MB/s) it's unclear that you'd stand to gain that much.

If you change the drive entirely to an M.2 NVME drive then you'd gain in performance and would become performance-limited by the Thunderbolt 1 ports. Basically you'd be operating around double your current speed, and likely half of what the M.2 NVME drive was capable of.

So far I've been pleased with my setup. I didn't buy the M.2 NVME drive to act as the new system drive, but to have a fast "scratch" disk for media editing, as my 512 GB internal SSD is becoming limiting. The NVME drive, basically running over Thunderbolt 2 (thanks to the Thunderbolt 3 enclosure connecting via the TB3 ports on the TB3 hub) reads and writes somewhere around 1,300 MB/s. My internal Mac SSD reads a bit faster at 1,600 MB/s and writes much slower, at 500 MB/s. Overall there's a performance gain, and when I can use the drive on an actual Thunderbolt 3 or Thunderbolt 4 port it should get even better. For reference, I'm using a Samsung EVO 870 NVME drive in a Yottamaster TB3 enclosure.
 
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Souponastick270

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Original poster
Mar 21, 2016
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Citadel Island
I don't think it will work as you're intending. From Apple's adapter support page:


One possible work-around would be to get a Thunderbolt hub. This is what I have done to power a Thunderbolt 3 enclosure (in my case, a CalDigit TS3+ hub) with a M.2 NVME drive with my 2015 iMac (which has Thunderbolt 2 ports). The Thunderbolt hub does also have USB ports. If you're just looking to have accelerated USB speeds (or the ports), the CalDigit Elements Thunderbolt 4 hub might be a better choice.

As to whether you'd gain much... hard to say. I'm guessing your USB 3 ports are operating at 5 Gbps (625 MB/s) - you'll lose some speed to overhead, but that's already nearing the max speeds for your drive (according to Crucial's website, around 560 MB/s read and 510 MB/s write). Even if you jump up to Thunderbolt 1 speeds (10 Gbps, or 1250 MB/s) it's unclear that you'd stand to gain that much.

If you change the drive entirely to an M.2 NVME drive then you'd gain in performance and would become performance-limited by the Thunderbolt 1 ports. Basically you'd be operating around double your current speed, and likely half of what the M.2 NVME drive was capable of.

So far I've been pleased with my setup. I didn't buy the M.2 NVME drive to act as the new system drive, but to have a fast "scratch" disk for media editing, as my 512 GB internal SSD is becoming limiting. The NVME drive, basically running over Thunderbolt 2 (thanks to the Thunderbolt 3 enclosure connecting via the TB3 ports on the TB3 hub) reads and writes somewhere around 1,300 MB/s. My internal Mac SSD reads a bit faster at 1,600 MB/s and writes much slower, at 500 MB/s. Overall there's a performance gain, and when I can use the drive on an actual Thunderbolt 3 or Thunderbolt 4 port it should get even better. For reference, I'm using a Samsung EVO 870 NVME drive in a Yottamaster TB3 enclosure.

Good catch, didn't see that the adapter isn't USB C compatible, so that shoots that idea down.

Yeah I'm not a millions miles off max speed for the read/writes on the Crucial: (this was BlackMagic results last year after setting up the SSD after two runs)
First Read: 427.3
First Write: 419.4

Second Read: 428.3
Second Write: 417.7

So from my understanding then, if I skip have the hub as it's not super essential to my set up, so long as I have a TB3/NVMe enclosure and not a USB C enclosure then that adapter should in theory work no ?

"As a bidirectional adapter, it can also connect new Thunderbolt 3 devices to a Mac with a Thunderbolt or Thunderbolt 2 port and macOS Sierra or later."
https://www.apple.com/shop/product/MMEL2AM/A/thunderbolt-3-usb-c-to-thunderbolt-2-adapter?
 

mdgm

macrumors 68000
Nov 2, 2010
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The reason to get a hub/dock is that the Apple bi-directional adapter doesn't supply bus power. So if your external drive doesn't have a separate AC power supply you need the hub/dock to provide power to the external drive.

The Apple adapter is the only bi-directional TB3 to TB2 adapter.
 
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Souponastick270

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The reason to get a hub/dock is that the Apple bi-directional adapter doesn't supply bus power. So if your external drive doesn't have a separate AC power supply you need the hub/dock to provide power to the external drive.

The Apple adapter is the only bi-directional TB3 to TB2 adapter.

Ah ok I'm with ya now, I think, so the chain would be:

iMac TB1 > TB1/2 Cable > TB2 to TB3 adapter > Externally powered TB hub < TB3 Cable < TB3/NVMe Enclosure
 

joevt

macrumors 604
Jun 21, 2012
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As to whether you'd gain much... hard to say. I'm guessing your USB 3 ports are operating at 5 Gbps (625 MB/s) - you'll lose some speed to overhead, but that's already nearing the max speeds for your drive (according to Crucial's website, around 560 MB/s read and 510 MB/s write).
USB 3.0 uses 8b/10b encoding (takes 10 bits on the wire to transmit a byte), so the actual amount of data is max 4 Gbps (500 MB/s) but with USB protocol overhead, the max is more like 450 MB/s.

Even if you jump up to Thunderbolt 1 speeds (10 Gbps, or 1250 MB/s) it's unclear that you'd stand to gain that much.
Thunderbolt 1 is 10.3125 Gbps using 64b/66b encoding, so 10 Gbps max.
USB 3.1 gen 2 is 10 Gbps using 128b/132b encoding, so 9.7 Gbps = 1212.12 MB/s but with USB protocol overhead, the max is ≈1000 MB/s.
Although USB 10Gbps is less than Thunderbolt 1 (by 0.3 Gbps), the actual bottleneck will be in the PCIe tunnelling over Thunderbolt 1 (≈830 MB/s) to communicate with the USB bus in the Thunderbolt 3 or 4 hub that the USB to NVMe enclosure is connected to.

If you change the drive entirely to an M.2 NVME drive then you'd gain in performance and would become performance-limited by the Thunderbolt 1 ports. Basically you'd be operating around double your current speed, and likely half of what the M.2 NVME drive was capable of.
I'm not sure you'll see a big difference between USB and NVMe over Thunderbolt 1. The tunnelled PCIe bottleneck to communicate with the NVMe device in the Thunderbolt NVMe enclosure will be the same.

Does iMac 2012 support booting NVMe? If not, then you can add the NVMe efi driver to an EFI partition and have the Driver#### and DriverOrder NVRAM variables point to it so it loads early.

Does the iMac 2012 USB efi driver know how to boot a USB 3.1 gen 2 device? Maybe, since USB 3.0 and USB 3.1 gen 2 both use XHCI (extended host controller interface). It could boot at 10 Gbps. If it boots at 5 Gbps, then it will switch to 10 Gbps when the OS driver loads.

A USB enclosure will be compatible with more computers.

There exist enclosures that can do both USB and Thunderbolt depending on the computer you connect it to. there are two variations:
1) an enclosure with a Thunderbolt port that can be connected to a Thunderbolt controller or a USB to NVMe bridge - either of which is connects to an NVMe device. They may call this USB4 but it's just Thunderbolt 3 + USB 3.1 gen 2. It can do NVMe at 3000 MB/s or USB at 1000 MB/s.
2) an enclosure with a Thunderbolt port connected to a Titan Ridge Thunderbolt 3 controller with a USB hub connected to a USB port of the Titan Ridge controller. The Titan Ridge can connect as USB or Thunderbolt, but the USB hub means that it can do only 1000 MB/s in either case (except for Thunderbolt devices connected to the downstream Thunderbolt port of the Titan Ridge controller).

I've only seen one person use a Thunderbolt 4 hub with a Thunderbolt 2 Mac so maybe it will work with Thunderbolt 1. Big Sur may be required for all functionality of the hub to work though? There is no OS loaded yet during boot so there may be different functionality between EFI and macOS. It will be interesting to see if all the Thunderbolt ports of a Thunderbolt 4 hub work during Startup Manager (hold the Option Key at boot) and macOS.
 
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PaulD-UK

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Oct 23, 2009
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I use a Glyph Thunderbolt 3 dock, which has an internal NVMe slot with a WD Black NVMe 1TB SSD, with my 2012 MacBook Pro 15" with TB1. This works fine as the boot drive with MacOS High Sierra (now Mojave/Catalina), giving 826MB/s read - 868MB/s write with Blackmagic Disk Test.
Connected via the Apple TB3><TB2 adapter.
 
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joevt

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Jun 21, 2012
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I use a Glyph Thunderbolt 3 dock, which has an internal NVMe slot with a WD Black NVMe 1TB SSD, with my 2012 MacBook Pro 15" with TB1. This works fine as the boot drive with MacOS High Sierra (now Mojave/Catalina), giving 826MB/s read - 868MB/s write with Blackmagic Disk Test.
Connected via the Apple TB3><TB2 adapter.
Interesting. I guess it's an Alpine Ridge based dock since it's limited to DisplayPort 1.2? The NVMe is using only two PCIe lanes but that's good enough for Thunderbolt 1 and Thunderbolt 2. What are the other two PCIe lanes for? There's a 10 Gbps USB port, so I guess there's an ASMedia ASM1142 (limited to 8 Gbps by PCIe 3.0 x1)? There may be a Fresco Logic FL1100 for the 5 Gbps ports (4 Gbps data because USB 3.0 and because PCIe 2.0 x1). The ASM1142 has two USB ports but only one port is labeled 10 Gbps? Maybe one of the type-A 5Gbps ports is connected to the ASM1142 and can actually do 10 Gbps? I guess the Ethernet port is a USB to Gigabit Ethernet adapter and not a PCIe device.
 

PaulD-UK

macrumors 6502a
Oct 23, 2009
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System Report identifies the Glyph dock internals as an ASMedia ASM1142 USB 3.1 controller branching into (1) a generic USB 2 hub for audio in/out and (2) a generic 4 port USB 3.0 hub for the SD card reader and the USB 3.0 ports. I can't test the speed on the front port labelled USB-C 10.
Gigabit ethernet comes from PCI to an Intel I210 T1 Controller.

I bought the dock for the practicality of its real-world functionality and feature set (mainly the internal NVMe slot), not its benchmark superiority...
 

joevt

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Jun 21, 2012
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System Report identifies the Glyph dock internals as an ASMedia ASM1142 USB 3.1 controller branching into (1) a generic USB 2 hub for audio in/out and (2) a generic 4 port USB 3.0 hub for the SD card reader and the USB 3.0 ports. I can't test the speed on the front port labelled USB-C 10.
Gigabit ethernet comes from PCI to an Intel I210 T1 Controller.
Ok, that makes more sense (PCIe ethernet is probably preferable compared to USB ethernet). The layout is like this:
- PCIe: 2x for NVMe, 1x for ASM1142, 1x for Ethernet.
- The ASM1142 has two ports, one is 10Gbps, and the other is connected to a four port 5 Gbps hub: 1) audio, 2) SD card, 3) USB port, 4) USB port.

A USB 3.x hub usually always consists of a USB 2.0 hub and a USB 3.x hub - a device will connect to the USB 3 hub if the host supports USB 3 and the device supports USB 3.
The audio device is a USB 2.0 device so it connects to the USB 2.0 hub. The host in this case is the ASM1142 chip.

I believe a USB 3.x hub does not convert a USB 2.0 downstream device to USB 3.0 upstream - instead, connecting multiple USB 3.x hubs in a chain means there's an entirely separate USB 2.0 path from host to USB 2.0 leaf device. That also means all USB 2.0 devices share the same 480 Mb/s bandwidth and don't affect the bandwidth of the USB 3.x devices connected to other ports of the hub.

Therefore, max total bandwidth of all USB devices connected to the ASM1142 is 7.9 Gbps. SD card and two USB ports are limited to a total of 4 Gbps (as good as you can get for a single USB 3.0 port). Audio is separate from those but not from the 7.9 Gbps. The Thunderbolt port can do USB 10 Gbps so that would be the first port to use for a 10 Gbps USB device (unless you're using the Thunderbolt port for a display or another Thunderbolt device).

The important thing is that your Thunderbolt 3 dock can saturate Thunderbolt 3 with USB and NVMe (4 + 7.9 + 15.75 = 27.65 is greater than 24 Gbps).
 

PaulD-UK

macrumors 6502a
Oct 23, 2009
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Good info - thank you.
Since everything is compromised by my iMac only having two Thunderbolt 3 ports, bandwidth sharing is a fact of life.
 
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Jack Neill

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Sep 13, 2015
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I am about to embark in this endeavor, I bought a 27" mid 11 iMac at Goodwill and am am going to try a Trebleet NMVE drive dock and a TB2 to TB3 adapter, I picked up a WD S750 NVME at Best Buy for 59.99 today and Im hoping for at least 600-800 R/W's
 
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Jack Neill

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Sep 13, 2015
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San Antonio Texas
I am about to embark in this endeavor, I bought a 27" mid 11 iMac at Goodwill and am am going to try a Trebleet NMVE drive dock and a TB2 to TB3 adapter, I picked up a WD S750 NVME at Best Buy for 59.99 today and Im hoping for at least 600-800 R/W's
So I got my NVMe dock today and I am now booting 10.13.6 off a WDSN750 on my 2011 27" iMac. Im getting about 550/720 R/W's. Was hoping for a little more, but honestly its more than fast enough and faster than cracking this thing open and using a 2.5" SSD and messing with the temp sensor although I was tempted to go the double drive and Raid 0 route. I also kinda wanted to leave the 1TB platter in place as a storage disk for music and photos. I also have 32Gb of ram coming tomorrow for this beast. Very happy with the results!
 
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Souponastick270

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Original poster
Mar 21, 2016
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Citadel Island
So I got my NVMe dock today and I am now booting 10.13.6 off a WDSN750 on my 2011 27" iMac. Im getting about 550/720 R/W's. Was hoping for a little more, but honestly its more than fast enough and faster than cracking this thing open and using a 2.5" SSD and messing with the temp sensor although I was tempted to go the double drive and Raid 0 route. I also kinda wanted to leave the 1TB platter in place as a storage disk for music and photos. I also have 32Gb of ram coming tomorrow for this beast. Very happy with the results!

Interesting, so is your NVMe enclosure thunderbolt 3 ? And are you running it through a powered dock into your thunderbolt 1 port on the iMac ?
 
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ThanosDJ

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Dec 27, 2023
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It is TB3 and it is powered, its connected via a TB2 to TB3 adapter.
Hello, can you inform me which is the model of the docking station that you bought? Do you know if it has a bootable option for Windows via bootcamp to your iMac? I want to buy this docking station too, or if you know a similar to this one with bootable options for MacOS and/or Windows via bootcamp.
 

Jack Neill

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Sep 13, 2015
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San Antonio Texas
Hello, can you inform me which is the model of the docking station that you bought? Do you know if it has a bootable option for Windows via bootcamp to your iMac? I want to buy this docking station too, or if you know a similar to this one with bootable options for MacOS and/or Windows via bootcamp.
Its a Trebleet dual NVMe enclosure, not really a docking station. It worked fine for booting from TB1/2 ports with a USB C adapter. Even with TB1 I got 800+ R/Ws. Anything external powered is a must as TB1 doesn't provide bus power.

I have been thinking about one of these lately.

 

ThanosDJ

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Dec 27, 2023
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Its a Trebleet dual NVMe enclosure, not really a docking station. It worked fine for booting from TB1/2 ports with a USB C adapter. Even with TB1 I got 800+ R/Ws. Anything external powered is a must as TB1 doesn't provide bus power.

I have been thinking about one of these lately.

Thank you for your quick reply, but do you have a link with the one that you use to see the specifications of the enclosure that you use? Also if it was an enclosure how did you give power supppy to this enclosure? It didnt require power supply in order to work? Do you know if it supports boot option for Windows via bootcamp or can you suggest another one that supports this option? I also want to boot in Windows too.
 

Jack Neill

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Sep 13, 2015
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San Antonio Texas
Thank you for your quick reply, but do you have a link with the one that you use to see the specifications of the enclosure that you use? Also if it was an enclosure how did you give power supppy to this enclosure? It didnt require power supply in order to work? Do you know if it supports boot option for Windows via bootcamp or can you suggest another one that supports this option? I also want to boot in Windows too.
This is the one I have. I don't have any input as far as Windows. I don't use BootCamp as I have dedicated Windows machines, I personally have zero use for Windows on Mac lol. I tried the Arm 11 in Parallels on my M1 but it was kind of pointless with my Strix and a Zephyrus sitting on my desk.

 

ThanosDJ

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Dec 27, 2023
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This is the one I have. I don't have any input as far as Windows. I don't use BootCamp as I have dedicated Windows machines, I personally have zero use for Windows on Mac lol. I tried the Arm 11 in Parallels on my M1 but it was kind of pointless with my Strix and a Zephyrus sitting on my desk.

I have seen it but it says on their website that it doesnt support boot for Windows. But i want the dual boot option. So do you have any suggestions for an enclosure or a docking station that supports dual boot option (boot for Mac and Windows too)?
 

Jack Neill

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Sep 13, 2015
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San Antonio Texas
I have seen it but it says on their website that it doesn't support boot for Windows. But i want the dual boot option. So do you have any suggestions for an enclosure or a docking station that supports dual boot option (boot for Mac and Windows too)?
I don't really, but in my experience, "not supported" and "doesn't work" are not the same thing. I can attest as I own both, that a TB2 enclosure like the LaCie and the WD dual drive work fine for booting without power and are not that expensive to buy and try, both of those solutions only net a R/W of about 300 with a SATA SSD, which can be fine for most applications. I have both of these and took them apart and put SSD's in them. The WD was a little harder to disassemble, but the LaCie was super easy.


 
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ThanosDJ

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Dec 27, 2023
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I don't really, but in my experience, "not supported" and "doesn't work" are not the same thing. I can attest as I own both, that a TB2 enclosure like the LaCie and the WD dual drive work fine for booting without power and are not that expensive to buy and try, both of those solutions only net a R/W of about 300 with a SATA SSD, which can be fine for most applications. I have both of these and took them apart and put SSD's in them. The WD was a little harder to disassemble, but the LaCie was super easy.


Thanks for the suggestions, so the speed of these too are faster than your trebleet enclosure? So as i understand they do not need extra power supply to work, is that correct? And sorry to insist, but do you know if they support dual boot option (for mac os and Windows)? It is important for me to know. Will those speeds are better that the speeds on an internal ssd on the same imac mid 2011 27"?
 
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