Prerequisite

• Raspberry Pi 4 (4+GB RAM)

• Micro SD card 64GB

• 2x Integral USB 3.1 flash drives 128GB Or 2x USB 3.1 HDDs 1024GB

• OS: - Raspbian Bullseye

RAID Setup

FORMAT DRIVES

1. Insert drive and list existing partition tables :

    sudo fdisk -l
   

2. Unmount drive (if needed) :

    sudo unmount /media/pi/<HARD-DRIVE-LABEL>
   

3. Partitioning :

    sudo fdisk /dev/sda
   

4. Press the following Keys when prompted :

   [m] for help
   [o]
   [n]
   [p]
   [1]
   [Enter]
   [Enter]
   [w]

5. Formatting :

    sudo mkfs.ext4 /dev/sda1
   

   Press [y] when prompted.

   💡

   DO NOT MOUNT THE DRIVE

6. Repeat steps 1-5 above for other drives.

CREATE RAID ARRAY

• Update the system and install 'mdadm' RAID package :

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

• Find out the mount points for each drive :

    blkid
  

  OR

    lsblk
  

• Create RAID volume/array :

  Linear Mode

    sudo mdadm --create --verbose /dev/md0 --level=linear --raid-devices=2 /dev/sda1 /dev/sdb1
  

  RAID-0 (Stripe Mode)

    sudo mdadm --create --verbose /dev/md0 --level=stripe --raid-devices=2 /dev/sda1 /dev/sdb1
  

  OR

    sudo mdadm -Cv /dev/md0 -l0 -n2 /dev/sd[ab]1
  

  RAID-1 (Mirror Mode)

    sudo mdadm --create --verbose /dev/md0 --level=mirror --raid-devices=2 /dev/sda1 /dev/sdb1
  

  OR

    sudo mdadm -Cv /dev/md0 -l1 -n2 /dev/sd[ab]1
  

  RAID-4/5/6

    sudo mdadm --create --verbose /dev/md0 --level=4 --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1
  

    sudo mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 /dev/sdb1 /dev/sdc1 /dev/sdd1 --spare-devices=1 /dev/sde1
  

    sudo mdadm --create --verbose /dev/md0 --level=6 --raid-devices=4 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1
  

  RAID-10

    sudo mdadm --create --verbose /dev/md0 --level=10 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
  

• Confirm RAID array :

    cat /proc/mdstat
  

• Save RAID array :

    sudo -i  
    mdadm --detail --scan >> /etc/mdadm/mdadm.conf  
    less /etc/mdadm/mdadm.conf  
    exit
  

• Create file system :

    sudo mkfs.ext4 -v -m .1 -b 4096 -E stride=32,stripe-width=64 /dev/md0
  

  💡

  NOTE: To change advanced parameters after creation if needed :

    tune2fs -E stride=n,stripe-width=m /dev/md0
  

• Create a mount point and mount file system :

    sudo mkdir /mnt/raidx  
    sudo mount /dev/md0 /mnt/raidx
  

  💡

  NOTE: To change the owner of the mount point to pi :

    sudo chown pi:pi /mnt/raidx
  

• Check the content of the mounted file system :

    ls -la /mnt/raidx
  

• Confirm its capacity :

    df -h -x devtmpfs -x tmpfs
  

• Update the initial file system (Raspberry Pi uses a RAM disk image when booting up and we want to include our array) :

    sudo update-initramfs -u
  

• Check the UUID of the mounted file system :

    blkid
  

  OR

    ls -l /dev/disk/by-uuid
  

• Add to fstab (make the drive permanent and auto mount drive at boot) :

    sudo nano /etc/fstab
  

  Enter a new line before the bottom comments and add :

    UUID=(my_uuid) /mnt/raidx ext4 defaults,noatime 0 0
  

• Save and exit :

  [Ctrl+O]
  [Ctrl+X]

• Retrieve drive parameters and test speeds (optional) :

    sudo hdparm -I /dev/md0
    sudo hdparm -tT --direct /dev/md0
  

• Reboot

    sudo reboot
  

Useful commands/Manage Mode

$ cat /proc/mdstat: show the status of all RAID devices
$ mdadm --detail /dev/md0 : detailed information about RAID md0 (mdadm -D)
$ mdadm --detail --brief /dev/md0 : for shortened/brief details (mdadm -Db)
$ mdadm --query /dev/md0 : quick human-readable summary of RAID md0 (mdadm -Q)
$ mdadm --examine /dev/sdx: information about RAID component device sdx (mdadm -E)
$ mdadm --stop /dev/md0 : stop RAID device md0
$ mdadm --assemble --scan: restart/assemble RAID device

SET UP NAS

• Install SAMBA

    sudo apt-get install samba samba-common-bin
  

• Set up SAMBA password (for user pi) :

    sudo smbpasswd -a pi
  

• Edit SAMBA config file :

    sudo cp /etc/samba/smb.conf /etc/samba/smb.conf.bak  
    sudo nano /etc/samba/smb.conf
  

  Scroll down to the bottom of the file and add the following code to create NAS file share :

    # NAS Share Block  
    [NAS]  
    path = /mnt/raidx  
    comment = RPI4 RAID0 NAS Server  
    volume = NAS-Server  
    valid users = pi  
    read only = NO  
    guest ok = NO  
    public = NO  
    writable = YES  
    browsable = YES  
    ### -rwxr--r--  
    create mask = 0744  
    ### -rwxr-xr-x  
    directory mask = 0755  
    ### All hosts on the 192.168.142 subnet allowed:  
    hosts allow = 192.168.142.
  

• Save and exit :
  [Ctrl+O]
  [Ctrl+X]

• Check the configuration file for internal correctness :

    testparm
  

• Restart SAMBA service :

    sudo /etc/init.d/samba restart
  

  OR

    sudo service smbd restart
  

• Reboot

    sudo reboot
  

USAGE ON MAC

• Open Finder

• Menu "Go" ⟶ "Connect to Server..."

Address: [smb://rpi4/NAS]

• [Connect]

• Connect As:

• Registered User

Name: pi
Password: ●●●●●●●●

• [Connect]

APPENDIX

COMMANDS TO CHECK

$ rsync options source destination : remote/local file-copying tool
$ rsync -ahv /mnt/u1/ /mnt/u2/ : example of the above

RAID LEVELS

Number of Drives /
RAID Level Availability:

2 /
RAID-0 Stripe (Fastest, but no redundancy)
RAID-1 Mirror (Excellent redundancy, good speed)

3 /
RAID-0 Stripe (Fastest, but no redundancy)
RAID-4 Dedicated parity disk (Good speed & redundancy)
RAID-5 Block-level striping with distributed parity (Excellent speed & redundancy)

4 /
RAID-6 Block-level striping with two parity blocks distributed across all member disks (Excellent speed & redundancy)
RAID 10 (nested RAID 1+0) (Excellent speed and redundancy)

REFERENCES

⇒ mdadm(8) - Linux man page
⇒ How To Manage RAID Arrays with mdadm
⇒ Advantages and disadvantages of various RAID levels
⇒ RAID setup
⇒ A guide to mdadm
⇒ Characteristics of Linux RAID levels
⇒ Build your own Raspberry Pi NAS
⇒ How to set up a Raspberry Pi Samba Server
⇒ Build a Raspberry Pi RAID NAS Server – Complete DIY Guide
⇒ Partitioning, Formatting, and Mounting a Hard Drive in Linux