I was having trouble finding a guide/steps to setup a software RAID 1 while in the Ubuntu installer. I stumbled upon a blog post that had the steps written out very nicely however since it was written as a comment I thought people may overlook it when they are first scrolling through search results. I will list out his steps as well as include screenshots and a bit more information.
My Setup
I will be testing on my KVM setup however all the steps below apply the same as if the server was a physical server.
I have two drives that are both 200G. I plan to have them setup in a raid1 mirror that will have a partition table like this:
tfernandez@ubuntu-2:~$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
loop0 7:0 0 69.9M 1 loop /snap/lxd/19188
loop1 7:1 0 55.4M 1 loop /snap/core18/1944
loop2 7:2 0 31.1M 1 loop /snap/snapd/10707
sr0 11:0 1 1024M 0 rom
vda 252:0 0 200G 0 disk
├─vda1 252:1 0 1M 0 part
├─vda2 252:2 0 1G 0 part
│ └─md0 9:0 0 1022M 0 raid1
│ └─md0p1 259:0 0 1018M 0 part /boot
└─vda3 252:3 0 199G 0 part
└─md1 9:1 0 198.9G 0 raid1
└─md1p1 259:1 0 198.9G 0 part /
vdb 252:16 0 200G 0 disk
├─vdb1 252:17 0 1M 0 part
├─vdb2 252:18 0 1G 0 part
│ └─md0 9:0 0 1022M 0 raid1
│ └─md0p1 259:0 0 1018M 0 part /boot
└─vdb3 252:19 0 199G 0 part
└─md1 9:1 0 198.9G 0 raid1
└─md1p1 259:1 0 198.9G 0 part /
Tony Fernandez 