[hanzer]

I installed OpenBSD-6.4 onto a USB flash device and booted. $ dmesg | grep -i raid reports:

mfii0 at pci2 dev 0 function 0 "Symbios Logic MegaRAID SAS2208" rev 0x05: msi
mfii0: "LSI MegaRAID SAS 9266-4i", firmware 23.32.0-0009, 1024MB cache

When SL-7.5 is running, $ lspci -vvv | grep -i raid reports:

02:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 2208
[Thunderbolt] (rev 05)
        Subsystem: LSI Logic / Symbios Logic MegaRAID SAS 9266-4i
        Kernel driver in use: megaraid_sas
        Kernel modules: megaraid_sas

So it looks like this card uses the SAS2208 chipset and the mfii driver. Woohoo! The backup and install plan begins.

Thanks!