RAID 0: Mixing U.2 with U.3, TLC with QLC, PCIe 4 with PCIe 5, MCIO with retimer card

[fatherboard]

This is one question I wish I never had to ask, but due to product availability, I might end up buying different NVMe drives with a similar storage capacity for the RAID 0.
Would it work? What could go wrong if I combine in a RAID 0?:

• Western Digital Ultrastar DC SN655 → U.3 PCIe 4 TLC
• Solidigm D5-P5336 → U.2 PCIe 4 QLC
• Samsung BM1743 → U.2 PCIe 5 QLC

and some are connected via MCIO, and others using a retimer card e.g. the Supermicro AOC-SLG4-4E4T

 

[ca3y6]

U.3 vs U.2 shouldn't matter, it's all nvme unless you run U.3 through an HBA.

You will likely get the performance of the slowest drive in the array, minus overhead. So it's not a terrible outcome. How many disks in RAID0 are we talking about? Had bad experiences with HGST U.2 SSD which would occasionally drop on reboot. A RAID0 array wouldn't like that.

 

[fatherboard]

How many disks in RAID0 are we talking about?

In principle as many as the motherboards can accommodate and all in one array. In practice, I will start with 2 drives, and I keep adding drives until I reach a minimum of 6 drives connected through MCIO, then the rest, the other 16 drives, will be added with retimer cards in PCIe expansion slots, 4 drives on each card. This would make a maximum of 22 drives. Important to know that I do not have separate arrays. Any drive that is added joins the one and only array.

Had bad experiences with HGST U.2 SSD which would occasionally drop on reboot.

The drives you had bad experience with, were they made and labeled Western Digital as of 2018 or was it earlier?
If earlier then HGST had faulty drives before being acquired by WD, if as of 2018 then WD has messed it up.

unless you run U.3 through an HBA

Is a retimer card like the Supermicro AOC-SLG4-4E4T also an HBA?

The problem with Asrock Rack TURIN2D16-2T and Supermicro H13SSL-N is that they only have 3 MCIO slots = max 6 drives via MCIO. There rest can only be added with a retimer card e.g. Supermicro AOC-SLG4-4E4T.
and ASUS PRO WS WRX90E-SAGE SE can only handle 2 drives via SlimSAS and the rest again with retimer card Supermicro AOC-SLG4-4E4T.

 

[ca3y6]

The drives I had problems with were HGST SN100 and SN200. I am not saying this to imply that you will experience similar problems with the SN655, just that you can't assume every drive will be stable in a large RAID0 array.

by an HBA, I meant a tri-mode HBA, yours is a simple retimer, i.e. NVMe pass through.

My thoughts with one giant NVMe RAID array is that 1) of course I assume the data is either unimportant or backed up somewhere, 2) I think you will hit the performance limits of whatever RAID technology you are using or of the OS fairly quickly. You might want to make some tests in term of whether you can actually utilise the performance. If not you might be better off with some SAS SSDs, which consumes less power and scale up more easily.