When trying to install on later series M4 or M5 rack mount servers, the OS has trouble with the embedded raid controller and installing to the correct drives.
this document will help resolve the issue of the correct modules, and drives being loaded for redhat operating Systems.
Issue: Previously , in Red Hat 6.10 and below, the way to install was to map the Server installer ISO and then do a whole bunch of extra steps to get the drivers and os installed. further complicating things, In RHEL 7.1 and later, the file type of the dud.img driver image was changed to dd.iso. The Cisco IMC virtual drive mapper can map only one .iso file at a time, and only as a virtual CD/DVD.
Workaround: This procedure simplified the steps by renaming the dd.iso driver file to dd.img before mapping. This allows you to map the RHEL installation ISO as a virtual CD/DVD and the renamed dd.img driver file as a virtual floppy disk or virtual removable disk at the same time. RHEL still detects the dd.img as dd.iso; it is only the Cisco IMC virtual drive mapper that sees it as an img file. please note, upon installation wizard initialization the disk may show up as a separate disk / partition then what is wanted for install. this can cause confusion due to how linux modules are loaded on installer. to resolve this please follow the steps at the bottom of this document to preserve the disk nomenclature for M.2 install.
Follow the RHEL installation wizard to complete the installation.
When the wizard’s Installation Destination screen is displayed, ensure that LSI MegaSR is listed as the selection. If it is not listed, the driver did not load successfully. In that case, select Rescan Disc.
After the installation completes, reboot the target server.
Using Redhat options to preserve megasr raid as bootable os raid disks.
when installing, a common scenario is to have /dev/sda be the install. this is to make sure that the OS always has /dev/sda for /boot /boot/EFI and then lvm preserving data disks/luns for data only and OS luns to have the bootable options. since the m.2 drives use swraid, and hwraid is used for data, sometimes the installer will pick the wrong drive after install to boot to.