rpi raid

this document describes how to move the root directory of a RPI from the sd card onto a RAID array

config

I enable pcie gen 3 using raspi-config (advanced section)

sudo raspi-config

update firmware

sudo rpi-eeprom-update

update, upgrade, install mdadm

mdadm is used to create a SW RAID array

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install mdadm

create md (multiple device) disk

find the disks you want to add to your md device and change the second line accordingly

ls -al /dev/disk/by-path/
sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/nvme0n1 /dev/nvme1n1

check the progress of creation, i'd suggest waiting until building is finished

´watch -n 3 cat /proc/mdstat`

save md config

sudo su
mdadm --detail --scan /dev/md0 >> /etc/mdadm/mdadm.conf
exit

format md device as ext4

sudo mkfs.ext4 /dev/md0

rebuild initramfs

load some modules into kernel for md

these modules will be included when building the init ram fs so the md can be mounted

sudo nano /etc/initramfs-tools/modules

and add

raid1
raid0
md_mod
ext4

update initial ram filesystemm

up until now i've been able to just update:

sudo update-initramfs -u

copy the root fs to the md device

mount md device

sudo mkdir /mnt/clone
sudo mount /dev/md0 /mnt/clone

mount rootfs

get device from /etc/mtab or ls -al /dev/disk/by-path/ and change second command accordingly

sudo mkdir /mnt/rootfs
sudo mount /dev/mmcblk0p2 /mnt/rootfs

sync rootfs to clone

sudo rsync -axv /mnt/rootfs/* /mnt/clone

update bootloader params

sudo nano /boot/firmware/cmdline.txt

root= becomes your md device, add rootddelay=5 (or larger) if md takes a while to be built

console=serial0,115200 console=tty1 root=/dev/md0 rootfstype=ext4 fsck.repair=yes rootwait rootdelay=5

edit fstab on the clone to mount your md device on /

sudo nano /mnt/clone/etc/fstab

change the line to match your md device

/dev/md0 / ext4 defaults,noatime 0 1

BONUS: swapfile

striping and mirroring using nvme allows for high speed data transfer, since i'm runing some resource intensive services i've increased the size of my swap to 32GB

turn swap off and edit config

sudo dphys-swapfile swapoff
sudo nano /etc/dphys-swapfile

change config to

CONF_SWAPFACTOR=4
CONF_MAXSWAP=32768

turn swap back on

sudo dphys-swapfile swapon