Incomplete article. This is a work in process.

RAID setup

Assemble

This can be necessary when making other drive configuration changes that impact the drive device letters.

mdadm -A or --assemble <-- the assemble option, followed by the array device then the drive devices to be used in the array.

Example:
sudo mdadm --assemble /dev/md0 /dev/sdb1 /dev/sdc1

Save configuration for boot

After completion, save the configuration to the boot ram disk.

sudo update-initramfs -u -v

RAID decommission

Stop

The array is "disassembled" but no changes are made to the drives included in the array or configuration.

sudo mdadm --stop /dev/md0

Then to erase the array configuration on the drives included in the array so they are not rebuilt on the next boot.

sudo mdadm --zero-superblock /dev/sda1 /dev/sdb1

It might also be required to edit /etc/mdadm/mdadm.conf to remove the array configuration line.