M1 Mini Thunderbolt adapter speed issue

[FCX]

I've recently replaced my 2013 MacPro with an M1 Mini, and have noticed a drastic speed drop from my TB2 RAID. It was direct-connected to the trashcan, and is now connected to one of the TB3 ports on the back of the Mini via an Apple TB2 - TB3 adapter. The other port on the Mini is connected to an OWC Thunderbolt 3 dock, and that dock has my LG 5K/2K monitor plugged in.

The R/W speeds dropped nearly 50% with the 'upgrade'. The RAID is an Areca 8050T2 (8 bay, RAID6) - used to get about 900 MB/s, now getting about 450 MB/s. Still usable, but what happened??

 

[Fomalhaut]

Have you tried disconnecting the OWC hub to see if that makes a difference? (and connect to the monitor using HDMI)

Does the dock have a TB3 connector as well? I've found faster external disk performance connected to my CalDigit TB3 hub than connected directly to the Mini (although on another thread an OWC user complained of poor USB speeds, so it may make it worse).

Is the TB2/TB3 adaptor an active device? Have you assessed it's impact with other devices?

Are you able to test with other Intel TB3 machines (e.g. MBP16, iMac) to see if it's related only to the M1?

Most people note that external disk performance (particularly USB 3) is significantly worse (30-40%) on the M1 Macs compared to Intel Macs. I think TB3 is relatively unaffected, but it sounds like you may be having a issue with the TB2 to TB3 conversion being efficiently processed on the M1.

 

[FCX]

Have you tried disconnecting the OWC hub to see if that makes a difference? (and connect to the monitor using HDMI)

Does the dock have a TB3 connector as well? I've found faster external disk performance connected to my CalDigit TB3 hub than connected directly to the Mini (although on another thread an OWC user complained of poor USB speeds, so it may make it worse).

Is the TB2/TB3 adaptor an active device? Have you assessed it's impact with other devices?

Are you able to test with other Intel TB3 machines (e.g. MBP16, iMac) to see if it's related only to the M1?

Most people note that external disk performance (particularly USB 3) is significantly worse (30-40%) on the M1 Macs compared to Intel Macs. I think TB3 is relatively unaffected, but it sounds like you may be having a issue with the TB2 to TB3 conversion being efficiently processed on the M1.

 I haven't tried without the dock, will do that on Monday
 The dock has a pair of TB3 ports on the back (one is designated as host port, which the Mini is connected to). I've tried the RAID connected to the second port on the hub, and direct-attached to the Mini.
 The adapter is Apple's own adapter. I suspect it's active, but can't prove it.
 I've tested the RAID direct-attached to my 2013 MBP. Similar performance to the MacPro (it's pretty close).

I'll test without the dock on Monday, but I'm not expecting a different result. I can't run it that way day-to-day anyway, as the HDMI port won't do 5K.

The RAID is old, but reliable, and fast enough for now. Just wasn't sure if anyone else was seeing a slowdown with the Apple TB2 / TB3 adapter.

 

[giffut]

There are lots of indications that Apple seems to be not that straightforward about the thunderbolt compatibility/capability they implemented with the M1 platform. This is in regards to backward compabilities and especially implemented USB4 protocol standards.

As I understand it the thunderbolt controller on all M1 platforms is a in house design and seems to be less performant than the original/native intel one. And it seems to be not 100% true to specifications expected from the protocoll.

Basically, that means, that there are speed drops and incompatibilities to be expected in all performance scenarios, regarding mac Mini M1, Macbook Air M1 and iPad Pro M1 machines. The manufactors of third party thunderbolt devices aren´t to blame for this. They only have the official specifications to work with and are completely dependant on Apples willful and harming secrecy here.

It is unfortunate that Apple is silent on this rather significant issue.

 

[ddown54]

According to teardown videos it's a

Intel® JHL8040R Thunderbolt™ 4 Retimer so Intel item​

 

[giffut]

Those Retimers are only organizing the electrical signals and have no protocoll based function. They are, indeed, thunderbolt 4 capable, but Apple implemented only the thunderbolt 3 protocol. It is directly integrated in the M1 Soc. We don't have an explanation from Apple why they stayed on thunderbolt 3, as much as not implementing the full USB 4 standard.

 

[FCX]

Minor update - no appreciable difference in RAID speed without the OWC dock. The internal storage on the Mini is over 4x faster than the RAID fwiw.