Disk mount issue
I added a new disk, removed one on my workstation. It is running Ubuntu 20.04. Booted up, and the drive letters have changed, and the md number of a RAID 1 array changed. So I updated /etc/fstab and went to mount the /dev/md1 array. The mount command completes without error, but the disk did not mount. Turns out, needed to:
systemctl daemon-reload
Then the mount worked, and I could add the new disk to the RAID 1 array.