M4 Mac Mini - Thunderbolt PCIE Expansion

[DankeBrutus]

Has anyone set up their M4/M4 Pro Mac Mini with a PCIe expansion bay like the OWC Mercury Helios 3S or Startech 2TBT3?

If so how easy was it to set up? Any headaches with PCIe cards over Thunderbolt? I have my Mac Mini coming in a couple of weeks and originally was considering the OWC 1M2 or 4M2 for mass storage. Either a 4TB Crucial NVME in the 1M2 or four 1/2TB in the 4M2 for 4-8TB in RAID0. I already have a backup solution so no redundancy doesn't bother me. However, I read a thread here on Reddit where, I assume, an OWC employee was talking about the 4M2 versus the Mercury Helios 3S. An expansion bay like the Mercury Helios or the Startech variant with two PCIe slots are tempting for the versatility alone. For example, if in the future I no longer have a need for NVME PCIe adapters I can reuse the enclosure for networking. However, if these devices are unreliable or macOS limits what can be done, I already know an external GPU is out of the question, then I won't bother.

edit: forgot to write "if" in that last sentence.

 

[OWC_TAL]

ha I think you are looking at my comments there. Thunderbolt is a PCIe passthrough. It is the same technology regardless of the brand. Considering the millions of devices using Thunderbolt, I'd say it is a reliable as it gets. MacOS does not support Bifurcation, so if you are planning to use multiple PCIe devices in a box, make sure the card has a PCIe switch.

 

[DankeBrutus]

ha I think you are looking at my comments there. Thunderbolt is a PCIe passthrough. It is the same technology regardless of the brand. Considering the millions of devices using Thunderbolt, I'd say it is a reliable as it gets. MacOS does not support Bifurcation, so if you are planning to use multiple PCIe devices in a box, make sure the card has a PCIe switch.

Yes it was your comments I was looking at. I did not know about macOS no supporting bifurcation. From what I can tell that basically means it cannot handle more than one PCIe device at the same time?

If I am looking for pure storage would the 4M2 be the better option with all four M.2 slots occupied and in a RAID0 pool? Just judging by the on-paper specs on the OWC website the 4M2 is ~300MB/s faster than the Helios+PCIe NVME adapter card combination, assuming I also buy the OWC Accelsior.

 

[OWC_TAL]

From what I can tell that basically means it cannot handle more than one PCIe device at the same time?

It means any device either needs to natively split up the signals (Express 4m2 has no PCIe switch, but the Thunderbolt chipset is configured to give each SSD 1 lane and cannot be reconfigured) or must have a PCIe switch (the Accelsior has a PCIe switch). Cheap 4 bay PCIe SSD cards that contain no pcie switch will not work.

The Express 4m2 versus Helios + Accelsior 4m2 will have the same speeds in a RAID0. If you are using each SSD independently (non RAID), the Helios option will be 4x faster though, since each SSD gets 4 lanes.

So both achieve the same outcome in RAID0. Express 4m2 is smaller and less expensive. Helios3s+accelsior is larger and more expensive but has the benefits of A) likely a bit quieter, B) PD charging to host computer and C) can be repurposed for other use cases in the future compared to the express. Either is good.

 

[joevt]

From what I can tell that basically means it cannot handle more than one PCIe device at the same time?

Bifurcation requires a software configurable PCIe switch which can, for example, turn a x16 slot into four x4 slots. In a PC, this is usually inside the CPU which provides the x16 lanes?

Macs and Thunderbolt enclosures do not have software configurable PCIe switches that do bifurcation. To split a PCIe slot into multiple slots, a PCIe switch is required.

The Express 4m2 configures (by hardware or firmware) the PCIe switch of the Thunderbolt controller into four x1 slots.

The Accelsior 4m2 has a PCIe switch to convert an x8 slot to four x4 slots.

The Accelsior 4m2 is going to be more expensive because of the extra PCIe switch (plus the larger Helios Thunderbolt enclosure). It will be faster for individual NVMe devices since they will have x4 instead of x1. It might be slightly faster for RAID0 since it's easier for four x4 slots to fill an x4 connection than it is for four x1 slots. Or it might be slightly slower since an extra PCIe switch might add latency?

 

[EugW]

Has anyone set up their M4/M4 Pro Mac Mini with a PCIe expansion bay like the OWC Mercury Helios 3S or Startech 2TBT3?

If so how easy was it to set up? Any headaches with PCIe cards over Thunderbolt? I have my Mac Mini coming in a couple of weeks and originally was considering the OWC 1M2 or 4M2 for mass storage. Either a 4TB Crucial NVME in the 1M2 or four 1/2TB in the 4M2 for 4-8TB in RAID0. I already have a backup solution so no redundancy doesn't bother me.

Is RAID 0 actually desirable for you? Cuz you could just get the OWC 1M2 or similar single NVMe enclosure and a single 4 TB or 8 TB WD SN850X. I believe both the OWC 1M2 and the Colorii / Qwiizlab / Hagibis support dual-sided SSDs like the SN850X in those sizes.

 

[Beau Slim]

I don't have a proper PCIe enclosure, but when my TB NVMe enclosure arrived I tried various m.2 cards with my m1 air. I was surprised to find that macOS for ARM already had drivers for a couple SATA controllers.

Most things, though, didn't work at all. I found it very reminiscent of my old cheese-grater mac pro, where plugging things in was easy, but finding drivers was often impossible.

 

[DankeBrutus]

Is RAID 0 actually desirable for you? Cuz you could just get the OWC 1M2 or similar single NVMe enclosure and a single 4 TB or 8 TB WD SN850X. I believe both the OWC 1M2 and the Colorii / Qwiizlab / Hagibis support dual-sided SSDs like the SN850X in those sizes.

For the most part I could take it or leave it. Like I said in the OP the 1M2 is on the table. However, having something like the 4M2/Helios would be beneficial because I'll have both the Mac Mini and my MacBook Pro. Being able to have both devices plugged in at the same time and work off the same data pool could be helpful. Of course I could just turn on file sharing for the Mini and serve the 4M2/Helios RAID pool to my home. That would be more convenient but not as fast.

Also where I am an 8TB SN850X is $1000. And you wouldn't be getting those peak 7000MB/s speeds anyway with Thunderbolt 3. If I had a need for 8TB then four 2TB Crucial P3+ comes up to about $650.

 

[joevt]

Being able to have both devices plugged in at the same time and work off the same data pool could be helpful

You cannot connect a NVMe via Thunderbolt to two different Macs at the same time. The OWC Helios is not a NAS (Network Attached Storage device).

One of the Macs will own the NVMe. i.e. The NVMe will appear as connected to one Mac as a NVMe PCIe device. That Mac can probably share the different file volumes of the NVMe over Thunderbolt to the other Mac (you need to enable Thunderbolt networking and File Sharing).