Sure, it is perfectly possible, it just does not make much sense. You would be going back to 2018 Pi3 days. With CM4 you are better off with using pci-e which has enough bandwidth available for 2-4 gigabit ports at full speed. And if you need more pci-e devices (like wireless) you can add pci-e switch and still the solution will have better throughput than using usb 2.0.The RPi CM4 has USB 2.0, and it's perfectly possible to connect additional Ethernet.
Sorry, but you cannot use a PCIe switch with an NVMe SSD and gigabit Ethernet controllers (or other devices) on the CM4. The bootloader on the CM4 does not currently support booting an OS from an NVMe SSD when storage is connected via a PCIe switch. Officially, the bootloader does not support loading the system from an NVMe SSD through a PCIe switch. viewtopic.php?t=375595
Yes, but: only the boot partition needs to be in front of the PCIe switch. The root partition and everything else can be behind it. Nothing mandates that the boot and root partitions be on the same device.
As I sit writing this I have a CM4 based NAS with a PCIe switch 2 x SATA cards, 1 x USB 3 card, and 5 drives next t me. One of those SATA drives contains the root filesystem.
The "trick" is to put the boot partition on SD/eMMC/USB2 and the required drivers into the initramfs. There's little to no performance hit in practice as once boot has completed the boot partition is only ever accessed manually or for some updates and config changes.
Statistics: Posted by thagrol — Thu Dec 05, 2024 5:55 pm