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Build a Raspberry Pi RAID NAS Server – Complete DIY Guide

Build a Raspberry Pi RAID NAS Server – [UPDATED 2020]

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2020-05-26: This guide is now updated to reflect some bug fixes and changes in mdadm and Samba.

Introduction

Today I’ll show you how to build a Raspberry Pi 3/4 RAID NAS server using USB flash drives and the Linux native RAID application mdadm, along with SAMBA so the drive will show up as a normal network folder on Windows PC’s. It’s an intermediate tutorial and shows you how to create a Linux RAID array which is a good skill to have.

Hardware Requirements

Raspberry Pi

You can use Raspberry Pi’s from version 2 onward, so 2B, 2B+, RPi 3/4 are fine, but I recommend the latest Raspberry Pi 4 with 4GB RAM. You’ll also need a good quality micro-USB power pack suitable for the Raspberry Pi you’re using, if in doubt, just buy a combo pack that comes with case, power pack and other goodies.

USB Flash Drives

We will be using USB2.0 flash drives for our RAID array, however you can purchase USB3.0 drives if you’re using a Raspberry Pi 4 (which has 2 USB3.0 ports) and RAID levels 0 or 1. The drives should all be the same size and preferably the same manufacturer for a good RAID array however, if you have an odd one out, just make sure it’s the same size or larger than the smallest drive.

In terms of drive size, your budget will be the determining factor, so just get what you can afford. Remember that with RAID-0 you get the total amount of all drives put together, so 2x 64GB drives will give you 128GB. RAID-1 will halve your total capacity, so 2x 64GB drives will give you 64GB, and RAID-5/6 will give you roughly 2/3 of total capacity, so 3x 64GB drives will give you 128GB of storage. RAID-10 will halve your total capacity, so 4x 64GB drives will give you 128GB storage (more about RAID levels further below).

RAID Levels

The number of drives you have with determine what RAID level you’ll be able to create. I suggest 3 (or more) drives which is the minimum required for a RAID-4/5 array that offers a good balance between redundancy and speed. If you only have 2 drives, I suggest using RAID-0, and even though there is no redundancy, RAID-0 rarely fails on solid state media. I have had my workstation running on SATA-3 SSD RAID-0 for years and it never skips a beat, but If you’re storing important files, go with RAID-1.

If you’re confident in your Linux skills you can create a RAID-10 array with 4 drives, which is 2 sets of RAID-1, then each set is used to form a RAID-0 array giving you the benefit of speed and redundancy (I will show you how to create all types of Linux RAID arrays).

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)

Once you’ve chosen a desired RAID level, let’s move onto Install/Update Raspbian and mdadm.

Installing Raspbian

Now we need to prepare our MicroSD card, install Raspbian, update the system and install mdadm Linux RAID. You will need a MicroSD card of 8GB or more and the application Etcher to transfer the .img file to it (Etcher supports Windows, Linux and MAC).

  1. Download the latest version of Raspbian Lite from raspberrypi.org
  2. Click on and extract the .img file and take note of it’s location
  3. If not already installed, download and install Etcher for Windows, Linux or MAC
  4. Insert your MicroSD card into a card reader, close any automatic windows, prompts or alerts
  5. Fire up Etcher which should detect the MicroSD card automatically (important! if you have multiple choices, be sure to choose the SD card we are working with)
  6. Click on the Select Image button, navigate to your Raspbian .img file, select it and/or click Open
  7. Once you’re sure you have everything right by double checking, click on the Flash! button
  8. Etcher will now start the flashing process, click Yes to the Windows prompt, and close any automatic alerts/windows that appear shortly afterwards
  9. Flashing should take about 5 minutes, then you’ll be presented with the “Flash Complete!” dialog
  10. Close Etcher, remove the card reader and MicroSD card
  11. Insert the MicroSD card into your Raspberry Pi

Raspbian Initial Setup

Now we need to do some initial setup of Raspbian, so go ahead and hook up a screen, keyboard and power up your Raspberry Pi and remember, on first boot your RasPi will automatically expand the file system to fit your MicroSD card size, then it will reboot. Once rebooted, login with username: pi password: raspberry

raspi-config Options

Now we’ll do some basic setup options for our RasPi NAS server, so enter the following and use raspberry for the password prompt:

sudo raspi-config

Then change the following:

  • Note* Use the Arrow keys to move up and down, use Enter key to select/confirm, use Tab key to select Cancel or Finish
  • Select “Change User Password” and change user:pi’s password
  • Select Hostname, then type RASPINAS for host-name (or anything you want) hit Ok
  • Select Interfacing Options > SSH, then Yes to enable
  • On Home Screen, hit Tab key until the <Finish> item is selected, hit Enter to reboot
  • You Raspberry Pi is now configured

Step-by-step screenshots of the above process:

Update & Install MDADM

Now we just need to update Raspbian and install the mdadm RAID package:

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

Setup Drives and RAID Volume

Just to make things easier for identifying our USB drives, we need to format and label each one sequentially:

  1. Windows
  2. Insert one of your USB drives (close any automatic windows)
  3. (Win7,XP,Vista) Go to Start > Computer (Win8,10) search “File Explorer” and open top result
  4. Right-click on the USB drive icon, then select Format
  5. In the Format window, change the following options: File system: NTFS, Volume label: USB01
  6. Now click the Start button, then Yes to alert box
  7. Repeat this process for each USB drive you want to use, increment Volume label: to USB02, USB03 etc
  1. MAC OS X
  2. Insert one of your USB drives (close any automatic windows)
  3. Go to Finder > Applications > Utilities > Disk Utility
  4. Locate the USB drive from the left hand-side and select it
  5. Click on the Erase tab and choose the following options: Format: ExFAT, Name: USB01
  6. Now click on Erase button, then confirm the Erase on the alert box
  7. Repeat this process for each USB drive you want to use, increment Name: to USB02, USB03 etc
  1. Linux (Ubuntu/Debian)
  2. Insert one of your USB drives (close any automatic windows)
  3. Open “All applications” icon bottom-left of your screen, then choose Utilities > Disks
  4. Select the USB drive from left side panel, then click the Gears icon, select Format partition
  5. Choose the following options: Erase: Don’t overwrite existing data (quick), Type: NTFS, Name: USB01
  6. Now click Format… button, then confirm by clicking Format button on alert window
  7. Repeat this process for each USB drive you want to use, increment Name: to USB02, USB03 etc

Now it’s time to insert your USB drives into your Raspberry Pi, it doesn’t matter which drive goes where. We need to find out the mount points for each drive using the following command:

sudo blkid

Which should produce something like the following:

pi@RASPINAS:~ $ sudo blkid 
/dev/mmcblk0p1: LABEL="boot" UUID="CDD4-B453" TYPE="vfat" PARTUUID="498dcd43-01" 
/dev/mmcblk0p2: LABEL="rootfs" UUID="72bfc10d-73ec-4d9e-a54a-1cc507ee7ed2" TYPE="ext4" PARTUUID="498dcd43-02" 
/dev/sda1: LABEL="USB01" UUID="8A44B0F244B0E1DD" TYPE="ntfs" PARTUUID="01411281-01" 
/dev/sdb1: LABEL="USB02" UUID="2CF48901F488CE90" TYPE="ntfs" PARTUUID="bd5d9029-01" 
/dev/sdc1: LABEL="USB03" UUID="A8CE3E46CE3E0D56" TYPE="ntfs" PARTUUID="0fb30d0e-01" 
/dev/sdd1: LABEL="USB04" UUID="3AC2CC7DC2CC3F3F" TYPE="ntfs" PARTUUID="0fb30d2b-01" 
/dev/mmcblk0: PTUUID="498dcd43" PTTYPE="dos" 
pi@RASPINAS:~ $

We need to confirm the mount points of our USB drives, most of the time it will be /dev/sda1, /dev/sdb1, /dev/sdc1 and /dev/sdd1

/dev/sda1: LABEL="USB01" 
/dev/sdb1: LABEL="USB02" 
/dev/sdc1: LABEL="USB03"
/dev/sdd1: LABEL="USB04"

If you have different mount points than shown here, it doesn’t really matter, you’ll just need to replace the code snippets with the mount points you have. It also doesn’t matter if the drive labels are out of order, just so long as they match up to your mount points.

Depending on how many drives you have, choose your RAID level and follow the instructions for your chosen level below.

Setup RAID-0 Volume

Enter the following code to setup two or more USB drives into a high-performance RAID-0 array in parallel, replacing --raid-devices=X with the number of drives you’re using, and /dev/sda1 /dev/sdb1 with your mount points:

(Note for RAID-0 arrays: If you get error: “mdadm: RUN_ARRAY failed: Unknown error 524” this is a bug due to drives not being exactly the same size for RAID-0 which has been fixed but Raspbian hasn’t updated yet).

sudo mdadm --create --verbose /dev/md/vol1 --level=0 --raid-devices=2 /dev/sda1 /dev/sdb1

If I were using 4 drives in my RAID-0 array the code would be as follows:

sudo mdadm --create --verbose /dev/md/vol1 --level=0 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

Setup a RAID-1 Volume

To setup a redundant RAID-1 array using two drives, enter the following code:

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

Setup RAID-4/5/6 Volume

To setup a redundant RAID-4, RAID-5 with three drives, or RAID-6 array with four drives, use the following code, replacing --level=X with the RAID level you want:

sudo mdadm --create --verbose /dev/md/vol1 --level=4 --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1

If I wanted a RAID-5 array using three drives and a hot spare, I would use the following code:

sudo mdadm --create --verbose /dev/md/vol1 --level=5 --raid-devices=3 /dev/sda1 /dev/sdb1 /dev/sdc1 --spare-devices=1 /dev/sdd1

Setup RAID-10 Volume

To setup a fast, redundant RAID-10 (aka Nested RAID-1+0) use the following code:

sudo mdadm --create --verbose /dev/md/vol1 --level=10 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

For more info on complex RAID arrays, see the mdadm Wiki.

Confirm your RAID Array

Now let’s confirm all went well creating your RAID array with the following command:

sudo mdadm --detail /dev/md/vol1

Which should produce something like this:

pi@raspberrypi:~ $ sudo mdadm --detail /dev/md/vol1
/dev/md/vol1:
           Version : 1.2
     Creation Time : Mon May 25 06:19:08 2020
        Raid Level : raid1
        Array Size : 7808000 (7.45 GiB 8.00 GB)
     Used Dev Size : 7808000 (7.45 GiB 8.00 GB)
      Raid Devices : 2
     Total Devices : 2
       Persistence : Superblock is persistent

       Update Time : Mon May 25 06:23:01 2020
             State : clean, resyncing
    Active Devices : 2
   Working Devices : 2
    Failed Devices : 0
     Spare Devices : 0

Consistency Policy : resync

     Resync Status : 14% complete

              Name : raspberrypi:vol1  (local to host raspberrypi)
              UUID : 9ca39f48:7c165518:5b186d64:c1ca774e
            Events : 2

    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1

Save your RAID array

Raspbian won’t let us save the RAID array as user:pi even using sudo, so we need to temporarily change to root account, enter the following:

sudo -i

Now we can save our RAID array by entering the following code:

mdadm --detail --scan >> /etc/mdadm/mdadm.conf

It’s also good to confirm it was saved by viewing the config file nano /etc/mdadm/mdadm.conf and look for something like this at the bottom of the file:

# This configuration was auto-generated on Fri, 19 Jan 2018 08:14:18 +0000 by mkconf 
ARRAY /dev/md/vol1 metadata=1.2 name=RASPINAS:0 UUID=0d7c55bd:ae5f8fbc:0e048a15:79de5064

Then exit from root user:

exit

Create File System

You have a number of choices when it comes to Linux file systems, but I will be using the EXT4 file system as it’s the best choice for our RAID array. If you want to learn more about some of the flags (stride, stripe-width, block options) see this article. The following code will produce an EXT4 filesystem with a block size of 4096kb, stride of 32, a stripe-width of 64 and will leave 1% free so it won’t fill up and cause issues (replace /dev/md/vol1 with your RAID array name):

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

If successful, you should see the following output (accounting information can take a minute or two):

pi@RASPINAS:~ $ sudo mkfs.ext4 -v -m .1 -b 4096 -E stride=32,stripe-width=64 /dev/md/vol1 
mke2fs 1.43.4 (31-Jan-2017) 
fs_types for mke2fs.conf resolution: 'ext4' 
Filesystem label= 
OS type: Linux 
Block size=4096 (log=2) 
Fragment size=4096 (log=2) 
Stride=32 blocks, Stripe width=64 blocks 958464 inodes, 3829760 blocks 3829 blocks (0.10%) reserved for the super user 
First data block=0 Maximum filesystem blocks=2151677952 117 block groups 32768 blocks per group, 
32768 fragments per group 8192 inodes per group Filesystem UUID: 394fd8f2-7b2a-474f-8e58-48b81a6ca8fb 
Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208 
Allocating group tables: done 
Writing inode tables: done 
Creating journal (16384 blocks): done 
Writing superblocks and filesystem accounting information: done 

pi@RASPINAS:~ $

Now mount the file system so we can access it using the following command:

sudo mount /dev/md/vol1 /mnt

We need to automatically mount the file system at boot, so let’s find out the UUID of our mounted file system by entering the following command:

sudo blkid

Which should produce something like the following:

pi@RASPINAS:~ $ sudo blkid 
/dev/mmcblk0p1: LABEL="boot" UUID="CDD4-B453" TYPE="vfat" PARTUUID="498dcd43-01" 
/dev/mmcblk0p2: LABEL="rootfs" UUID="72bfc10d-73ec-4d9e-a54a-1cc507ee7ed2" TYPE="ext4" PARTUUID="498dcd43-02" 
/dev/mmcblk0: PTUUID="498dcd43" PTTYPE="dos" 
/dev/sda1: UUID="0d7c55bd-ae5f-8fbc-0e04-8a1579de5064" UUID_SUB="f954ff33-87db-4e26-8be9-e978aa0ef815" LABEL="RASPINAS:0" TYPE="linux_raid_member" PARTUUID="bd5d9029-01" 
/dev/sdb1: UUID="0d7c55bd-ae5f-8fbc-0e04-8a1579de5064" UUID_SUB="eea15556-4e0a-1985-163a-064670df9db2" LABEL="RASPINAS:0" TYPE="linux_raid_member" PARTUUID="01411281-01" 
/dev/md/vol1: UUID="394fd8f2-7b2a-474f-8e58-48b81a6ca8fb" TYPE="ext4" 
/dev/sdc1: UUID="0d7c55bd-ae5f-8fbc-0e04-8a1579de5064" UUID_SUB="2a8456d7-6fea-eba2-7728-ebd20aa238e5" LABEL="RASPINAS:0" TYPE="linux_raid_member" PARTUUID="0fb30d2b-01" 
/dev/sdd1: UUID="0d7c55bd-ae5f-8fbc-0e04-8a1579de5064" UUID_SUB="51019b58-995f-cf35-f6c3-33d61a104d76" LABEL="RASPINAS:0" TYPE="linux_raid_member" PARTUUID="0fb30d0e-01"

The item we’re after is the UUID of /dev/md/vol1: (if your volume name doesn’t show, it’ll be called “md127” or similar, this is a bug in mdadm, but continue the guide using the name you gave your array) which in my case is 394fd8f2-7b2a-474f-8e58-48b81a6ca8fb but yours will be different. Highlight and copy the UUID and paste into a text editor, then add it to fstab and backup the original fstab just in case:

sudo cp /etc/fstab /etc/fstab.bak 
sudo nano /etc/fstab

Just before the bottom comments, make a space and enter the following on a single line (replace your_uuid with the UUID of your file system):

UUID=your_uuid /mnt ext4 defaults 0 0

So, my fstab entry would look like this:

UUID=394fd8f2-7b2a-474f-8e58-48b81a6ca8fb /mnt ext4 defaults 0 0

Now save Ctrl+O and exit Ctrl+X.

By default, root user owns the /mnt file system with no read or write permissions, so we need to change that as follows:

sudo chown -R pi:pi /mnt
sudo chmod -R 0777 /mnt

Install and Setup SAMBA

SAMBA is a Windows file sharing system that runs on Linux, works flawlessly, and is easy to setup too. Let’s install SAMBA and then configure it with the following command (choose Yes to window prompt during installation):

sudo apt-get install samba samba-common-bin -y

After SAMBA finishes installing, let’s add user:pi and share password by entering the following command (enter a password at the prompts):

sudo smbpasswd -a pi

Which should produce the following result if successful:

pi@RASPINAS:~ $ sudo smbpasswd -a pi 
New SMB password: [ENTER PASSWORD] 
Retype new SMB password: [CONFIRM PASSWORD] 
Added user pi. 
pi@RASPINAS:~ $

Before we start altering the SAMBA config file, let’s make a backup:

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

Now we edit the smb.conf file:

sudo nano /etc/samba/smb.conf

Scroll down to the bottom of the file using your arrow key, then add the following code to create your NAS file share:

# NAS Share
[NAS]
path = /mnt
comment = RasPi NAS Share
valid users = pi
writable = yes
browsable = yes
create mask = 0777
directory mask = 0777

The save Ctrl+O and exit Ctrl+X. Now let’s make sure our changes work, enter the following:

testparm

Which should product the following (if you want a full output, press Enter at the prompt):

pi@RASPINAS:~ $ testparm 
Load smb config files from /etc/samba/smb.conf 
rlimit_max: increasing rlimit_max (1024) to minimum Windows limit (16384) 
WARNING: The "syslog" option is deprecated 
Processing section "[homes]" 
Processing section "[printers]" 
Processing section "[print$]" 
Processing section "[NAS]" 
Loaded services file OK. 
Server role: ROLE_STANDALONE 

Press enter to see a dump of your service definitions

If the line reads “Loaded services file OK.” then you’re good to go.

Finally, we need to restart the SAMBA service by with the following command:

sudo systemctl restart smbd

Connect to your NAS

(Please Note: Windows is a p.i.t.a when it comes to accessing your NAS if you get it wrong the first time, so please make sure you get it right first time. If you get any errors like “…Disconnect all previous connections to the server or shared resource and try again.” see this guide.)

Now let’s connect to your NAS share and make it automatically show up in your Network drive. Open File Explorer then click on the Network item on left-side window pane. Click inside the address bar, then type \\RASPINAS (or whatever you chose for a host-name during Debian setup, if you’re unsure enter the hostname command) and hit Enter

Map Network Drive

You can make your NAS a permanent drive if you like. Open File Manager and go to Computer/This PC, click the Computer tab, then Map Network Drive. Enter the host-name of your NAS followed by the shared folder name: \\RASPINAS\NAS and choose a drive letter. If successful you should be redirected to the NAS shared folder. You can now go to My Computer/This PC and see your network drive there permanently.

Summary

Well I hope this guide has shown you some cool RPi and Linux stuff and that you had fun 🙂 Something to think about is adding a USB hub to expand the drive number capacity instead of forking out big $$ for large capacity USB drives. You can also add normal 2.5″ or 3.5″ SATA drives via a USB adapter, see this article. If you have any questions or comments, leave them below.

Reader Interactions

Comments

  2. Nick says

    Hi, Thanks for making a creat tutorial. I was able to complete everything and get my volume mounted to my Windows system. I am however running into a permissions issue when I try to create a new folder or access the folder that is already inside the NAS folder. I did add my user ‘pi’ in the samba configuration per the tutorial and I can use the credentials to mount the volume. Is there another place I need to set permissions to allow my windows system to store things on this mounted partition?

    Thanks,
    Nick

    Reply

    • Richie says

      Hi Nick, no worries glad you liked the guide. When you got to the “Connect to your NAS” step, were you prompted to enter username and password on Windows? And did you check the “Remember Credentials” checkbox?

      Cheers!
      Richie

      Reply

      • Pocoil says

        Hello Richie,
        Thank you for this well written tutorial !
        I seem to have the same Issue as Nick. I am not able to write nor read anything inside the “NAS” folder.

        Here is my NAS config inside smb.conf:

        # NAS Share
        [NAS]
        path = /mnt
        comment = RasPi NAS Share
        valid users = pi
        browseable = yes
        read only = no
        writeable = yes
        create mask = 0777
        directory mask = 0777

        While browsing I have seen both syntaxes for browsable/browseable and writable/writeable so guess the issue doesn’t lie there.

        Thanks for your help,
        Pocoil

        Reply

      • Janik says

        I had the same problem. My solution was:

        sudo chmod 777 /mnt

        i know 777 is a bit over kill and unsecure but it’s okay for my need’s.
        btw is thre a way to first connect this to usb drives to an “normal pc” copy the data onto them and then connect them to a pi so the first time setup is faster because i wan’t to use them as a offside backup

        Reply

  3. Thomas Lynn Skean says

    Hi!

    In the “Setup Drives and RAID Volume” section of the guide, why choose NTFS as the filesystem to place on the individual drives when performing the step in Linux? Is there any disadvantage to choosing ext4?

    I like your guide quite a bit. Thanks!

    Reply

    • Richie says

      Hi Thomas, thanks mate. The only reason we need to format the drives is so we can give them a label (in this case USB1/2/3/4) so as to visually identify them on Linux. NTFS is overwritten with EXT4 anyway but the labels remain.

      cheers!
      Rchie

      Reply

    • Richie says

      Hi Kelly, speed overall isn’t great, this guide is more leaning toward learning Linux software RAID and it’s a really fun project to do. I haven’t tried on new RasPi 4 yet which has USB3.0 so I am guessing there would be speed improvements there.

      cheers!
      Richie

      Reply

  5. Lance says

    I think “sudo /etc/init.d/samba restart”
    Needs to be changed to:

    sudo service smbd restart
    sudo service nmbd restart

    Thanks for the article!

    Reply

  6. Nathan says

    I’m excited to give this a shot in my own home as I’ve never built a RAID before. With that said, how would I rebuild this raid in the event one drive crashes? Is it as easy as plugging in a new blank drive and the software does it for me? or would I have to rebuild the project?

    Reply

  7. Andy says

    Thank you so much for this comprehensive step-by-step guide! I am thinking about building my own RAID-5 using your tutorial. However, I also want to know if one of the drives fails, e.g. sdb1 fails, then how do I do hot swap and rebuild?

    Reply

  8. Dan says

    Hi Richie, very interesting guide. I’m seriously considering this among my options, but planning to build a much larger array to store media and photos. Wonder if you’re aware if the Pi has a limit on the size of drives which can be connected? My intent is to use 4 x either 1TB or 2TB drives, probably 2.5″ notebook drives on USB-to-SATA cables. Using spindle drives rather than SSD it should be possible to do this really on the cheap, like around $40 per drive (for real brand name like WD) and 8-dollar USB cables. If the Pi can hack it, this could provide a 3-4 TB RAID-6 NAS for under $200.

    Do you know/think Pi would cooperate in such a scenario?

    Reply

    • Richie says

      Hi Dan, no problems. Speed is the only issue, although I have not tested this guide with the RPi 4 (4GB RAM) which may be faster. As Raspbian is simply a modified version of Linux I can’t see any issue with the larger drives. If it turns out the setup isn’t speedy enough you could use a mini-itx mobo that has a PCIe x8 oe x16 slot and a RAID card (like a LSI MegaRAID 9260 8i) on the cheap.

      Would love to hear how it goes Dan.

      Cheers!
      Richie

      Reply

          • Dan Martin says

            Hey Richie, so my first go isn’t looking too good. Two problems I’m finding so far:

            1) the drives don’t seem to be auto-mounting … at least, when I do the “blkid” command I’m not getting any mounts but the original SD card. If I do a tail -f /var/log/messages (found it on another thread) I see evidence of the drives being recognized (as sda, sdb, sdc, etc), but not mounted.

            2) probably more importantly, it looks like by the time I mount the 3rd drive I’m over the current that the Pi wants to pass through the USB bus. I’m actually seeing an “overcurrent” fail on the messages occasionally. And if I connect all 4 drives the power lights on all four (but not on the Pi itself) actually go off.

            I’m thinking perhaps a powered USB3 hub might solve problem #2 … what do you think? And do I just need to manually mount the disks to solve problem #1?

          • Richie says

            Hi Dan, ahh yes the Pi won’t be able to handle the amps for a mechanical drives so you’ll need to power via hub or directly (sorry I didn’t think of that earlier). The power issue may have also caused the mount to fail on boot. Once the power has been sorted, it should auto mount as there is no real difference between mechanical and flash drives in terms of filesystems.

            Choosing the right powered USB3 hub will be important, the best I can find is the Orico here.

            That should fix the problems you’re experiencing.

            cheers!
            Richie

  10. Dan Martin says

    One further question though … I see you referenced the mount “fail on boot.” Are USB drives not hot-mountable on the Pi?

    Reply

  11. Dan Martin says

    Hey Richie, SUCCESS!! I’ve just completed a successful install using your instructions, creating a RAID-5 array on a Pi 4, 4GB using 4 1-TB Seagate drives as noted above, with the Sabrent powered USB hub to power the drives. I opted for 4-drive RAID5 configuration since this is just backup and a hot spare is probably overkill (I’m gambling that I don’t lose more than one drive at a time in the array, obviously). Resulting drive is 2.68 TB. Connecting to a wired gigabit ethernet LAN, I just transferred a 1GB file from a SSD on my desktop computer (Windows 10 Pro) to the NAS in about 17 seconds.

    Two things I had to do that weren’t exactly the same as your directions:

    1) The command “sudo /etc/init.d/samba restart” did not work because on this version of Raspian the Samba daemon is named “smbd.” There is no “samba” in /etc/init.d.

    2) I had to manually chown my /mnt folder to pi, as it started out owned by root. This may be because I used the “sudo bash” cheat to do all the other commands from root so I didn’t have to type “sudo” every time, so perhaps it was my fault. But it’s worth your readers knowing that if you can connect to the drive from Windows and read, but not write, checking permissions/ownership may fix the problem.

    Other than that though, your instructions worked flawlessly once I supplied sufficient power to my drives.

    One other thought you may consider adding to your instructions: I like being able to use a GUI for administrative purposes so I installed webmin following the instructions for the APT repository at http://webmin.com/deb.html.

    Thanks for this excellent reference!

    Reply

    • Dan Martin says

      One more addition … since I care about being able to monitor my array, I also installed smartmontools which doesn’t come with Raspian by default. Once installed it’ll also be active in Webmin. This is to be able to query SMART parameters for the drives and know if they’re threatening to crash.

      Just because I wasn’t having enough fun already though, it turns out that Seagate drives tend to be unsupported using smartmontools due to their implementation of UAS. As a consequence one of several methods for addressing a “quirk” in the USB driver are necessary in order to enable SMART on those drives. The documentation for this quirk is at https://www.smartmontools.org/wiki/SAT-with-UAS-Linux, and the instructions for inserting the quirk into the Raspberry Pi configuration are at https://www.raspberrypi.org/forums/viewtopic.php?t=245931.

      What I actually did was to find the vendor and product IDs of the drives by using lsusb. In my case the Seagate drives were 0bc2:2343. So then I used nano to edit the file /boot/cmdline.txt to add the string in front of what was already there, save and reboot. Presto! smartctl can now query the drives.

      Reply

    • Richie says

      Hi Dan, awesome work mate and integrating Webmin for monitoring is a great idea. I think if anyone else is following this it would be optimal to use SSD’s instead of mechanical drives as they draw much less power and many times faster: https://www.storagereview.com/node/2567. You’d still need a powered hub for best performance though. You could also use large capacity USB3.0 flash drives without the need for extra power (512GB are available but $$$). What would be ideal is to source or build a powered USB3.0 rack for 4x SSD drives, let the Pi run the RAID array as usual, all inside a compact unit. eBay or some more obscure websites may have such a rack (looking for just the USB3 rack and powered hub without any OS).

      Cheers!
      Richie

      Reply

      • Dan Martin says

        I agree Richie. The only reason to go with mechanical spindles is cost for storage. That said, my objective was a cheap NAS, and at that we have succeeded.

        Reply

      • Dan Martin says

        Hey Richie, just one thought further … to your suggestion of large-capacity flash drives. I’m thinking theoretically not experimentally here, but it seems to me possible that one might prefer to use a USB 3.0 hub (powered or not) even with those, since the Pi has only 2 USB 3.0 ports and two USB 2.0. The performance bottleneck of 2.0 would, it seems to me, reduce RAID performance more than a hub at 3.0. True?

        Reply

  12. Dan Martin says

    Sorry, I typoed up above … the string I added to /boot/cmdline.txt is “usb-storage.quirks=0bc2:2343: ” (without the quotes)

    Reply

  13. John Morgan says

    Hi Ritchie, I also needed to use ‘sudo service smbd restart’ to restart samba as Lance posted but other than that, all seemed to be good and went smoothly. However, I cannot for the life of me get Win 10 to see the pi. It a Pi 4 with 2 drives (ssd & sata both on powered hub) set as a mirror. I used ‘mdadm –detail /dev/md0’ to verify the drives are good and they are syncing, so your system is working fine. Any tips about getting Windows to play would be most appreciated (other than binning it!)

    Regards,
    John

    Reply

    • John Morgan says

      I take it all back! If I had only read your”Connect to your NAS” correctly, it would have worked the first time.
      Nice work, Ritchie.

      John

      Reply

  14. Yuri Volodin says

    1 When suddenly powering off, file system on microsd can be corrupted.
    2 If your system is not readonly, your microsd will die soon.
    The question:
    If I move writable part of OS to RAID will I be safe from the above fails?

    Reply

  15. Benoit says

    Hi,
    Just a noob question…
    Is it possible to follow this tutorial using 2x 1To of SSD drives with external energy supplied ?
    Thanks

    Reply

  16. Ed Johnson says

    Hi. On RaspPi4b with 4 Gb RAM, the command to restart Samba is just:
    “sudo samba restart”
    I was also able to use “sudo /etc/init.d/smbd restart”, but I don’t think that restarted the nmbd daemon.
    Same thing with “sudo service smbd restart”. It worked but didn’t restart nmbd.

    Reply

  18. Evan says

    Ive completed the guide, it is very good.
    If anyone can find the drive at the end look at the pictures.
    Dont have “Network\\hostname” only type \\hostname in the address bar.

    Ive set up a RAID 5 with 10 500GB HDDs.

    Only problem that i am having now is saving data to the NAS.
    From windows 10, i am inside the mounted network drive “NAS (//sparkserver)” and press RMB to quickly add a .txt file.
    I recieve a message that reads:

    “You need permission to preform this action”
    “NAS(\\sparkserver)”
    “Space free: 3.57 TB”
    “Total size: 3.57 TB”
    Buttons: “Try Again” and “Cancel”

    Try Again refreshes the message and cancel closes it.

    testparm results read:
    [NAS]
    comment = RasPi NAS Share
    path = /mnt
    read only = no
    valid users = pi

    Any thoughts?

    Reply

  19. LT says

    I run into this error message when trying to setup a raid 1 volume, using (2) Seagate Expansion 1TB Portable Drive – 1TB, External Hard Drive, USB 3.0 – STEA1000400

    pi@raspberrypi:~ $ sudo blkid
    /dev/mmcblk0: PTUUID=”d4b0c6d3″ PTTYPE=”dos”
    /dev/mmcblk0p1: SEC_TYPE=”msdos” LABEL_FATBOOT=”RECOVERY” LABEL=”RECOVERY” UUID=”A070-7205″ TYPE=”vfat” PARTUUID=”d4b0c6d3-01″
    /dev/mmcblk0p5: LABEL=”SETTINGS” UUID=”2b530f44-2442-4fc7-97f7-9057e8b352d1″ TYPE=”ext4″ PARTUUID=”d4b0c6d3-05″
    /dev/mmcblk0p6: LABEL_FATBOOT=”boot” LABEL=”boot” UUID=”0B95-3D60″ TYPE=”vfat” PARTUUID=”d4b0c6d3-06″
    /dev/mmcblk0p7: LABEL=”root” UUID=”7b049bce-b185-4b25-bc0c-0f9c72a3870d” TYPE=”ext4″ PARTUUID=”d4b0c6d3-07″
    /dev/mmcblk0p8: SEC_TYPE=”msdos” LABEL_FATBOOT=”System” LABEL=”System” UUID=”3379-1328″ TYPE=”vfat” PARTUUID=”d4b0c6d3-08″
    /dev/mmcblk0p9: LABEL=”Storage” UUID=”8c20ddb3-5c93-4ccd-84ea-e5e580798dc2″ TYPE=”ext4″ PARTUUID=”d4b0c6d3-09″
    /dev/sda1: LABEL=”Seagate Expansion Drive” UUID=”F4E05762E0572A5E” TYPE=”ntfs” PTTYPE=”atari” PARTUUID=”10205715-01″
    /dev/sdb1: LABEL=”Seagate Expansion Drive” UUID=”C6AE8284AE826D2D” TYPE=”ntfs” PTTYPE=”atari” PARTUUID=”e5c552c6-01″

    pi@raspberrypi:~ $ sudo mdadm –create –verbose /dev/md0 –level=mirror –raid-devices=2 /dev/sda1 /dev/sdb1
    mdadm: super1.x cannot open /dev/sda1: Device or resource busy
    mdadm: ddf: Cannot use /dev/sda1: Device or resource busy
    mdadm: Cannot use /dev/sda1: It is busy
    mdadm: cannot open /dev/sda1: Device or resource busy

    Reply

  20. Raphael says

    Thanks a lot for your guidance!

    I belive though, that the Create File System Part misses a sudo:

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

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

    Further i had some issues with creating the raid array:
    sudo mdadm –create –verbose /dev/md0 –level=mirror –raid-devices=2 /dev/sda1 /dev/sdb1

    resulted in:
    mdadm: super1.x cannot open /dev/sda1: Device or resource busy
    mdadm: ddf: Cannot use /dev/sda1: Device or resource busy
    mdadm: Cannot use /dev/sda1: It is busy
    mdadm: cannot open /dev/sda1: Device or resource busy

    I could resolve this by un-mounting the volume in the File Explorer. Hope this helps other people 🙂

    Cheers

    Reply

  21. Steven Lundahl says

    Excellent, step-by-step article! Thanks! I did run into a couple issues along the way including the SAMBA restart issue mentioned by a previous writer. The biggest problem I had ultimately was an ownership permissions issue because I could see the NAS volume from Windows but not write to it. The volume was owned by root and I could not write to it so I used chown to change ownership to the pi user.

    Reply

  22. Donald W Lively says

    Excellent instructions.

    I was wondering what type of transfer speeds I should expect using a Pi 4 with 4 Gig Ram and a USB 3.0 drive enclosure for 4 3.5 drives. My drives are 7500 RPM SATA drives of 3TB each and when I configure them for a RAID 10 I end up with a little over 5TB of storage.

    When I try to copy over data off of my DROBO 5N connected via ethernet to the new NAS I set up, I am only getting speeds of around 2.7 to 3 MB per second which is taking forever. Is that normal or should I see better transfer rates or is there something I can tweak with SAMBA or on the Pi to make it faster?

    Thanks!
    Don

    Reply

  23. Kev says

    Excellent tutorial. I’ve got it running on a Pi 4 with 4x64GB USB sticks. It runs perfectly.

    I haven’t tried hot swapping one of the disks yet, need to learn how mdadm works before I start messing about. Have you tried it?

    Reply

    • Richie says

      Thanks Kev. I haven’t tried hot-swapping but I’m sure it’ll work fine, mdadm is a very robust RAID system.

      cheers
      Richie

      Reply

  24. Anthony Donaldson says

    What a great find this tutorial was and project for a PI.

    I have run into a issue while trying to build the RAID. I’m using a pi 4 and 2 x WD 4TB powered my books. Everything look great until I run “sudo mdadm –create –verbose /dev/md0 –level=stripe –raid-devices=2 /dev/sda1 /dev/sdb1”
    I get the following error:
    mdadm: super1.x cannot open /dev/sda1: Device or resource busy
    mdadm: ddf: Cannot use /dev/sda1: Device or resource busy
    mdadm: Cannot use /dev/sda1: It is busy
    mdadm: cannot open /dev/sda1: Device or resource busy

    Any ideas on what can be causing this? All assistance appreciated.

    Reply

    • Richie says

      Hi Anthony, so it may be related to your SATA drives and hidden partitions that WD put there. Can you try again except this time format the drives as follows:

      1. Plug both hard drives into your Windows PC via USB
      2. Type “CMD” into Windows search, then open Command prompt with Administrator privileges
      3. type: diskpart to run the DiskPart program
      4. Type: list disk and identify your 2 USB drives (be careful here! Make sure you know the DISK numbers!)
      5. Type: select disk # replacing # with your disk number
      6. Type: clean to fully clean the disk
      7. Repeat for other disk from step 4
      8. Begin the NAS guide again from step “Setup Drives and RAID Volume”

      Let me know how you go mate.

      cheers
      Richie

      Reply

      • Anthony Donaldson says

        Hi Richie,
        Thanks for the reply and I solved it simply by using gparted to unmount the drives. Once this was done I could then create the RAID.

        I think that as they were mounted MDADM was showing them as busy.

        It is now working fine and I’m just struggling with SAMBA. I created a folder\share called “Backup” and can map to the NAS and see created folders but cannot open the folders. It’s permission related according to Windows. I want to use the NAS for windows backups so still a work in progress.

        Thanks again for a great doc

        Reply

        • Richie says

          Hi Anthony, ok I have been through the guide and fixing some issues that have arised due to bugs and updates to mdadm and Samba, should be ready later today. One of the issues if file permissions which is why you’re getting that Windows error. It can be fixed by the following commands

          chown -R pi:pi /mnt
          chmod -R 0777 /mnt

          Hopefully that’ll fix it mate.

          cheers
          Richie

          Reply

  25. Alessandro says

    Many thanks for this article. I have 2 questions:

    – I already have 2 drives, same size and model, and I want to use them for a RAID 1. In particular, the first drive already has lots of precious data on it, the second is empty. Can I configure RAID 1 without format the first drive?
    What if I first copy all the files from Drive 1 into the second, before the setup? Should I then start working in RAID 1 in this condition?
    Or is it mandatory to start the RAID configuration with both the drives empty?

    – Let’s say I’ve set up my Raspberry with RAID 1 successfully. Then one day I unplug one drive and I use it on another PC. Say that I create/delete some files.
    Then I re-attach the drive into the Raspberry. Will the changes be replicated automatically on the second drive?

    Many thanks for the support

    Reply

    • Richie says

      Hi Alessandro, no problems glad you liked it. Unfortunately you can’t restore or save your data and make a RAID array, you’ll need to buy another drive big enough to hold the data and transfer to it, or just buy another drive and use that on the RAID array instead of your drive with the data.

      cheers
      Richie

      Reply

  26. Anthony Donaldson says

    Hi Richie,

    Just wanted to let you know that I ran thru the whole build again with the updated build guide and it has worked flawlessly.
    Thanks for the great guide and your kind assistance.

    I rate it 11 out of 10 mate 🙂
    Cheers
    Ant

    Reply

  27. Stephen Schmidt says

    I just received my first Raspberry Pi. I successfully set up mirrored drives. Decided that I want to add a drive and go raid 5. Can you tell me what I need to do? There is no data on the array yet. I am a Linux noobie. Thanks

    Stephen

    Reply

    • Richie says

      Hi Stephen, great stuff and congrats. You would need to delete the mirror, add the new drive, then create the RAID-5 array:

      sudo umount /mnt
      sudo mdadm --stop /dev/md/vol1
      mdadm --remove /dev/md/vol1

      Then create you RAID-5 array. I recommend starting fresh and start the guide from beginning including formatting the USB drives in Windows.

      cheers
      Rich

      Reply

  28. Wara says

    I tried Raid 0 and there is an ” Unknown error 524 “as it was mentioned in the steps it was a bug on raspberry pi so what i am looking for is there any exeptional method to use Raid 0 for 2 different sizes of usb drives without getting that error.

    Also, this tutorial is really helpful and thanks for producing such a creative tutorial.

    Thanks .

    Reply

    • Richie says

      Hi Wara, the only way I can see would be to force Raspbian to upgrade to the latest version of mdadm. but I was unable to find how to do this. I suggest posting on ServerFault as those guys are spot on with advice of this kind.

      Cheers
      Rich

      Reply

  29. Jim Harris says

    Great tutorial, but as usual I need a bit of help. When creating the file system it says “….(replace /dev/md/vol1 with your RAID array name):
    sudo mkfs.ext4 -v -m .1 -b 4096 -E stride=32,stripe-width=64 /dev/md/vol1…..” That is a bit confusing to me at least. I cannot find previously where the RAID array has been named. If not named already is the “/dev/md/vol1” the default name? Or, do I make a new name at this point? Thank you for the help.

    Reply

    • Richie says

      Hi Jim, ok so in the previous step you created the RAID volume, which is 2 or more disks acting as one. The volume name will be vol1 or the name you used when you created the array. The next step is to create the file system on vol1, so sudo mkfs.ext4 -v -m .1 -b 4096 -E stride=32,stripe-width=64 /dev/md/vol1. So they are two different steps.

      cheers
      Rich

      Reply

  30. Martin says

    Hi Rich,

    You’re a star for producing this guide. Thanks
    I’m a pi newbe as well …
    I’ve completed all of the steps successfully! 3rd attempt 🙂

    Now over to the windows 7. I get asked for the passwd and it bombs out on me saying;

    “\\NAS\nas is not accessible. you might not have permission to use this network resource…etc”

    i tried another users reply of “sudo chmod 777 /mnt” and your reply of checking the passwd remember box.
    neither worked …

    i’d be so grateful for this last bit of help 🙂

    Thanks again
    I’m at a loss.

    Reply

  31. Michael says

    Hi Richie,

    Awesome guide. Thank you so much for putting this together. I was able to get it up and running first try and happy so far.

    One issue I have run into and I’m not sure how to proceed. When I restart my pi I am getting an error: “Cannot open access to console. The root account is locked see sulogin(8) man page for more details.”

    It looks like prior to that when running through the startup there is a timeout waiting for the device after the “Started MD array monitor” and then failed dependency for /mnt and Local File Systems. I was able to get around this by editing the fstab file and commenting out the UUID (editing the file on my laptop). Then when I restart the pi with the updated file it will post fine without the NAS mounted. I undo the #, and re mount… but I’m wondering if there is a solution so I don’t have to do this every time? It seems like I’m missing something obvious here!

    Michael

    Reply

    • Richie says

      Hi Michael, thanks mate. I think this is due to user root not having a default password in Raspberry Pi OS. Try the following: sudo passwd root and enter a new password for root, then reboot and see if that fixes the issue sudo reboot

      let me know how you go.
      cheers
      Rich

      Reply

      • Michael says

        Hi Rich,

        I just tried this and unfortunately it is the same result. It is still fixable by # UUID on Fstab and remounting though so its actually not a bad workaround in the low chance it has to reboot. If you have any other ideas or think I may have incorrectly configured something though let me know and I’ll try again!

        Michael

        Reply

  32. Jason says

    Great work, I got my Pi Nas up! But I’m getting some mediocre speeds on my USB 3.0 external HDDs going to my Pi 4 (approx. 20MBps on file transfer). Any idea on what the issue might be? I checked out some of the resources you linked above, but it seemed more pertinent to Pi3 issues. Not sure if I’m overlooking something…

    Reply

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