Just wanted to loop back on this in case it helps someone else. Ended up getting a brand new 9211-8i controller off ebay for $35USD and then used using a standard Freedos USB stick made using Rufus I added the following files based off various guides I read;
- Shell_Full.efi which I renamed to shellx64.efi on the USB stick
- Installer_P20_for_UEFI from which I extracted the sas2flash.efi file.
- 9211-8i_Package_P20_IR_IT_Firmware_BIOS_for_MSDOS_Windows from which I extracted the 2118it.bin (for IT mode), 2118ir.bin (for IR mode) and mptsas2.rom
With all this on a USB stick in the back of my NAS along with the new 9211-8i controller in place with all disks disconnected I booted into the BIOS for my motherboard and selected the option to boot into the UEFI Shell. Once loaded into this command line shell I typed (minus what is in brackets);
- mount fs0: (to mount the USB as a file system, the file system number might be different for you so you may need to cycle through)
- fs0: (change to USB)
- dir (verify that USB contents are readable)
Following commands interfaces with your disk controller and can potentially brick it. By continuing you acknowledge all risk in doing so sits on you.
- sas2flash.efi -listall (verify your 9211-8i controller can be seen)
- sas2flash.efi -o -e 6 (wipes the 9211-8i BIOS, do NOT reboot once this has been completed)
- sas2flash.efi -o -f 2118it.bin -b mptsas2.rom (writes the latest P20 IT Mode firmware to the 9211-8i controller, swap out the 2118it.bin for 2118ir.bin in the command line argument for IR Mode. I don't want any RAID functionality at the controller level here, so I went with IT Mode so there is nothing getting in between OMV and the SATA disks)
After this I just put my OMV NAS back together and everything just worked. I have been thrashing the SAMBA file transfers and very happy to say that I am once again pretty much saturating my 1gbps network, so at this stage it is looking like it was a fading disk controller that was causing the disk drop outs and massively slowed file transfer speeds.
Hope this helps someone.