M.2 NVMe PCIe bus question

[Museicmn69]

Hi all, I’m getting a new Mac Pro 2019 model soon and was wondering if anyone had dealt with adding PCIe M2 NVMe drives. With my current machine I had a SSD drive for recording on one Thunderbolt port, and another drive on a separate Thunderbolt port for streaming libraries for virtual instruments. Then the main system drive ran the actual programs.

I’m looking to go with internal drives now. Cards like the SonnetTech 4x4 PCIe card can take 4 M.2 ssds and says it dedicates x4 lanes for each SSD. I’m thinking one SSD for recording, another for library streaming, then the other 1 or 2 just for storage.

So my question is would that be good for recording and streaming virtual libraries at the same time on 1 PCIe bus, or should I get 2 individual cards to keep separate on 2 different PCIe busses? Hope that makes sense?

 

[Steenamaroo]

Hi,
I have two Sata3 ssds on a PCI-E gen 2 X2 card. The theoretical max bandwidth there should be 1GB/s (for the pair) but in real world I see 750-800MB/s max.
I also have an NVME SSD on its own gen2 X4 card with theoretical max of 2GB/s but I see approx 1400MB/s each way.

Following on I think you can expect to see maximum real-world throughput of around 3000MB/s each way with the Sonnet on PCI-E gen 3, using 4 lanes per SSD, without raid.
True to that, Sonnet are advertising 12,000MB/s aggregate total bandwidth without raid.

For comparison I think Thunderbolt 3 would get to a maximum of around 2750MB/s and half that for thunderbolt 2.

In short it looks like the card can saturate the bus so the limiting factor is really the SSDs you put on it.
I don't think there's any advantage to buying multiple cards instead of the one.

I would, however, strongly recommend getting heatsinks for your SSDs.
I don't know why they aren't just fitted from the factory. Your typical NVME SSD will throttle under medium heavy use, limiting the speeds hard in order to keep temperatures down.

The heatsinks don't have to be fancy. You can get very cheap one-piece heatsinks with adhesive pads and fit them yourself.
I did that with mine and they never go over 35C or so, now.


Hope that's helpful.