I added two 8TB disks to my Ubuntu system and modified the BIOS to use Intel RST. In Ubuntu the two disks showed up as part of a RAID array, in the fdisk they show up individually as sda and sdb, but as part of a RAID array. I formatted each independently. After not being able to mount them, i switched the BIOS to ACHI. The two disks still existed as a RAID array within Ubuntu with the ACHI setting.

With ACHI set, disks are mounted automatically to /dev/dm-0 and /dev/dm-1. I cannot write to the disks and store files.

I’m going to give up on the RAID1 array for now, and just would like a single disk to work. How can I revert the system so that I can start over from scratch?