create-raid1.md

create raid with two usb disks

install tools

sudo apt-get install mdadm

list block devices

sudo blkid 

create raid

sudo mdadm --create --verbose /dev/md/vol1 --level=1 --raid-devices=2 /dev/sda1 /dev/sdb1

inspect raid config and persistent it

sudo mdadm --detail /dev/md/vol1
sudo mdadm --detail --scan >> /etc/mdadm/mdadm.conf

crate file system and mount it

sudo mkfs.ext4 -v -m .1 -b 4096 -E stride=32,stripe-width=64 /dev/md/vol1
sudo mkdir /media/raid1
sudo mount /dev/md/vol1 /media/raid1

create fstab link

sudo blkid

sudo cp /etc/fstab /etc/fstab.bak 
sudo echo "UUID=UUID-OF-RAID1-DEVICE /media/raid1 ext4 defaults 0 0" >> /etc/fstab