OMV 5 don´t detect raid or disk but 4 does it without any problem

Sry i can't help you, but i can confirm your problem.

I have also an PCIe Adapter with an Marvell 88SE9230.

With OMV4 everything worked and also with a clean Debian 10 installation.

During installation of OMV5 (with the .iso) i see all discs and raids,

but after the first reboot, everything is gone.

I can only see the discs, connected to the internal Sata ports, but nothing connected to the Marvell PCIe card.

Solution (for me)

I found out that CPU virtualisation can cause problems with the Marvell chip.

If you don't need it, deactivate it in BIOS.

I had the problem that my drives where reordered (sdX) between installation (Marvell worked) and regular boot (Marvell doesn't work).

After disabling VT-d and a new installation of OMV5, everything stays in place.

Thanks a lot! I had exactly the same problem on ASROCK J4125B-ITX with Marvell 88SE9230 in PCI-E. I spent hours googling and trying everything, then finally I came across this thread. Everything works as expected with CPU virtualisation disabled in BIOS.