One of my drives in my RAID died, so I went and bought a 3TB drive for a replacement. The RAID is only 1T, so I'll use the rest of it for something else.
It drives me nuts that every site out there describes in great detail how to do different things. Anyone can read the man page, or issue the parted "help mkpart" for example; but what I usually look for is a quick start. So, here's a quick rundown on how I re-set up the RAID drive. At the bottom is a full rundown on how I think I originally setup the RAID, but don't quote me on it. 😀
We run through the basic use of parted and mdadm.
Create and Add RAID Mirror
parted /dev/sdb mklabel gpt mkpart primary 1 1T set 1 raid on align-check mdadm --manage /dev/md10 -a /dev/sdb1 cat /proc/mdstat
# create a mirror with two devices mdadm --create /dev/md10 --force --level=1 --raid-devices=2 /dev/sdb1 /dev/sde1
That's really all there is to it. From there, you can just use /dev/md10 as you would any other drive or partition. You can use it as a raw disk with partitions, or turn it into an encrypted volume, or a physical volume for LVM, etc.
RAID Cheat Cheat
# create mirror with only one device mdadm --create /dev/md10 --force --level=1 --raid-devices=1 /dev/sdb3 # create a mirror with two devices mdadm --create /dev/md10 --force --level=1 --raid-devices=2 /dev/sdb3 /dev/sdd1 # grow and add a mirror instantly. mdadm --grow /dev/md10 --raid-devices=2 -a /dev/sdd1 # fail and remove a device mdadm --manage /dev/md10 --fail /dev/sdd1 mdadm --manage /dev/md10 -r /dev/sdd1 # turn a mirror with one disk into a striped array. mdadm --grow /dev/md10 --level=raid5 mdadm --grow /dev/md10 --raid-devices=2 -a /dev/sdd1