[GUIDE] How to install Ubuntu 18.04 Server on the My Cloud PR4100 NAS

Disclaimer: do this at your own risk. No fancy web gui here, just raw unix power.


  • a PC running Ubuntu 18 or similar… and some experience with unix.
  • USB flash drive (8GB+)
  • WD My Cloud PR2100/PR4100

If you’re lazy and in a hurry, skip the guide and go straight for the boot image at the end of the post.


sudo apt install qemu-kvm ovmf

Prepare a working directory

mkdir ubuntu && cd ubuntu

Copy the UEFI bootloader to a local file named bios.bin

cp /usr/share/ovmf/OVMF.fd bios.bin

Download the Ubuntu 18.04.1 server iso.

Find out the name of your USB flash drive with lsblk. I’ll use /dev/sdX here.
Boot the iso installer.

sudo kvm -bios ./bios.bin -cdrom <path_to_iso> \ 
         -drive format=raw,file=/dev/sdX -boot once=d -m 1G

It should mention TIANO CORE during boot and then enter a black grub screen to install Ubuntu.
Complete the installation with the defaults and any extra package that you may be interested in (e.g. Nextcloud).
Note down the user and password, you need it to login into the machine later.
At the end, it will reboot and ask you to remove the cdrom.
Just close the whole window to shutdown the whole virtual machine.
Then boot without cdrom straight from the USB flash drive.

sudo kvm -bios ./bios.bin -drive format=raw,file=/dev/sdX -m 1G

Login in the virtual machine and update packages if you like.

Ubuntu is now installed for a virtual network interface with the new udev persistent networking naming.
You’ll see the current network interface is called ens3 or similar.

ip addr show

This won’t work on actual My Cloud hardware.
Create the netplan configuration as follows

sudo editor /etc/netplan/01-netcfg.yaml
  version: 2
  renderer: networkd
      dhcp4: true
      dhcp4: true

This causes the NAS to get a dynamic IPv4 address on both of its onboard (eno) interfaces.

Example with static IP and bonding

Here’s how to combine the throughput of the 2 network interfaces on a single static IP address.

  version: 2
  renderer: networkd
      dhcp4: false
      optional: true
      dhcp4: false
      optional: true
      interfaces: [enp1s0, enp2s0]
      addresses: []
       addresses: [,]
        mode: 802.3ad
        mii-monitor-interval: 1

More info (static IP, bonding, …) on https://netplan.io

Hardware Control
Thanks to the research of Michael Roland and @dswv42 we now have full control over the fan, lcd, buttons and sensors. Ubuntu ships with the 8250_lpss module, so you don’t need to build a custom kernel.
The PMC is accessible at serial port /dev/ttyS5.
You need some packages from the universe repo.

sudo add-apt-repository universe
git clone https://github.com/WDCommunity/wdnas-hwtools
cd wdnas-hwtools
sudo ./install.sh

The Ubuntu boot disk is now ready. Shutdown with

sudo halt -p

and plug the USB drive in the PR4100 NAS.
Boot up and enjoy!


Download example boot disk image

Download my image here, unzip (use 7zip on winwods) and burn to a 16GB+ flash drive.
Direct unzip and write with

cat foo.img.gz | gunzip | dd of=/dev/sdX


Login: wdnas
Password: mycloud

Warning: risk for data loss when using the wrong device
To grow the file system to use the complete usb boot drive, delete the second partition.

sudo sgdisk /dev/sdX --delete=2

Create it again, it will automatically use all available space.

sudo sgdisk /dev/sdX --new=2

Refresh the partitions

sudo partprobe

Now that the partition has been resized, you can grow the file system. This is done on the second partition /dev/sdX2, not on the disk /dev/sdX.

sudo e2fsck -f /dev/sdX2
sudo resize2fs /dev/sdX2
Create a new ZFS array

Here’s a great overview on the core features of ZFS.
Now let’s create a ZFS array on the PRx100.

Insert your disks (hotplug is allowed). List them.

wdnas@wdnas:~$ lsblk -d
loop0          7:0    0 86.9M  1 loop /snap/core/4917
loop1          7:1    0 89.5M  1 loop /snap/core/6130
sda            8:0    0  1.8T  0 disk 
sdb            8:16   0  1.8T  0 disk 
sdc            8:32   0  1.8T  0 disk 
sdd            8:48   0  1.8T  0 disk 
sde            8:64   1 14.3G  0 disk 
mmcblk0      179:0    0  3.7G  0 disk 
mmcblk0boot0 179:8    0    2M  1 disk 
mmcblk0boot1 179:16   0    2M  1 disk 

Here we see sde is the USB boot disk.
Create a mirror pool over sda and sdbbased on the Ubuntu Tutorial.
It’s recommended to name your pool media.

sudo zpool create media mirror sda sdb

Alternatively, create a raidz pool over 4 disks. This is similar to a RAID5 pool, using 1 disk for parity.

sudo zpool create media raidz sda sdb sdc sdd

In order to use it, you need to create a file system (also called dataset) on the zpool. This is similar to a ‘share’ in the My Cloud OS.
Here’s an example

sudo zfs create media/pictures

The file system gets mounted automatically at /media/pictures.

or import existing data

SSH into My Cloud NAS running Ubuntu.

cat /proc/mdstat
sudo mdadm --assemble --scan

or if you used my FreeNAS image to create a ZFS array

sudo apt install zfsutils-linux
sudo zpool import

Follow the instructions.
It’s recommended to name your zpool ‘media’ so that the Ubuntu snap system can easily use it.

Prevent disks from spinning up every 10 minutes

Disable udisks2

Setup Nextcloud

I couldn’t explain it better than this Digital Ocean guide.
All data will be stored on the USB boot disk, which is not so interesting.
Here’s how to change the nextcloud snap data partition to your zfs pool.

First create a zfs dataset for nextcloud.

sudo zfs create media/nextcloud

Allow the nextcloud snap to use the zpool

sudo snap connect nextcloud:removable-media

Change the data path in /var/snap/nextcloud/current/nextcloud/config/autoconfig.php

sudo sed -i "s#'directory' => .*#'directory' => '/media/nextcloud/data',#" /var/snap/nextcloud/current/nextcloud/config/autoconfig.php

Restart nextcloud

sudo snap restart nextcloud.php-fpm

Now visit your nextcloud website and create the admin user.

Disable internal flash memory

If the internal flash memory is completely broken, you may be unable to restore the origal WD OS.
Installing Ubuntu is a solution, but you’ll see system freezes when polling the disks in the dmesg output.
A solution is to blacklist the mmc_block driver.

sudo editor /etc/modprobe.d/blacklist.conf

Add a line with

blacklist mmc_block


sudo update-initramfs -u

Great thanks to the “Tfl” user for helping me very much.
I have a really totally brick PR2100 with “probably internal flash is fried”
I do not know the exact way he did, but I now have the PR2100 with Ubuntu and NextCloud.
It seems that the PR2100 now works better than the original software.
Thank you once again.

Here’s what I used to setup a PR2100.

  1. Setup disks.
sudo apt install zfsutils-linux
sudo zpool create media mirror sda sdb
sudo zfs create media/nextcloud
ls -l /media/nextcloud      # verify it exists
  1. (re) Install nextcloud
sudo snap remove nextcloud
sudo snap install nextcloud
while [ ! -f $CFG ]; do echo -ne '.'; sleep 1; done
  1. Create admin account.
    Add a space in front of the command to prevent it from being recorded in your bash history!
  sudo nextcloud.manual-install admin someverysecretpassword
  1. Setup data dir
sudo snap connect nextcloud:removable-media
sudo sed -i "s^'datadirectory'.*^'datadirectory' => '/media/nextcloud/data',^" /var/snap/nextcloud/current/nextcloud/config/config.php
sudo snap disable nextcloud
sudo mv  /var/snap/nextcloud/common/nextcloud/data /media/nextcloud/data
sudo snap enable nextcloud
  1. Setup HTTPS
sudo nextcloud.occ config:system:set trusted_domains 1 --value=some.domain.com
sudo ufw allow 80,443/tcp
sudo nextcloud.enable-https lets-encrypt

Thanks for your effort!
How is the overall performance? Are the disks spinning all the time? or there is something similar to standby mode?
Are the USB ports working as in WD firmware?
What is the RAM usage, average CPU temp, FAN speed etc.?
Is there any web based admin panel? I found ajenti, but I’m not familiar with it. Do you have any suggestion?
I want to give a try but just want to make sure I’ll not be in trouble since I have been using customized WD firmware.

Spindown of the disks can be managed with hd-idle.
The disks spin when you access them of course… depends a bit what you install on them.
An external OS disk (on USB) is low noise anyway.

If you really need a GUI, you can install webmin. Here’s an overview. But as I said in the opening post… I don’t use a GUI.
Or see How do you run Ubuntu Server with a GUI? - Ask Ubuntu
I’d argue that nextcloud provides sufficient web gui once it’s installed.

You can safely test running Ubuntu from USB media, even access your data after import with mdadm, install nextcloud snap on USB … and when you’re not satisfied, shutdown and unplug the USB boot disk to go back to WD OS.

So what do you gain (if you know how to set it up)?

  • Run whatever you like, with the latest security updates.
  • Latest kernel, with plenty modules so USB ports support more than just disks
  • Full networking control. e.g. I’m running Algo VPN / WireGuard on it. The hot stuff of the moment.
  • VMs… not great but not impossible

I have tried your boot disk image, so far I liked it. I have couple of questions though.
Why the default FAN speed is at 810?
When does it increase and what is the interval? - Is there any configuration file?
Is the FAN increased on high CPU temp?
What is your CPU temp? On the high load I have seen 60-65C.

Now I want to build the img myself.

Is this above part done in VM? In the install.sh script, is it exiting after the below line (exit 1)? since the CPU is different.

lscpu | grep N3710
if [ ! $? ]; then
echo “Only the WD My Cloud PR2100 and PR4100 are currently supported in this installer”
exit 1

Are both ethernet cables plugged? Mine was only one cable, but it didn’t get IP. Then I inserted second cable, eventually it worked, but on LCD I got IP printed as 999 while the original IP was

hd-idle worked as expected.
webmin is good enough.


Thanks for all the feedback.

I suggest you skim through these files

  • wdhwdaemon/daemon.py
  • wdhwlibs/temperature.py
  • wdhwlibs/fancontroller.py
  • tools/wdhwd.conf

Feel free to modify it to your needs… but I am quite happy with the current behaviour.
Note that CPU temperature is usually 20 degrees higher than the disks and you need to ensure some minimal airflow in such a condensed box (hence the minimal rpm).

No I usually install the wdhw tools only on the box itself. The reason is the automatic shutdown in the wdhw tools when it detects unusual temperatures (or fails to get the temperature). The VM doesn’t have a PMC module to talk to, so the wdhwd may panic and go in a bootloop.

The LCD scripts are in /usr/local/lib/wdhwd/scripts/show_lcd.sh
There too many options here so you need to adapt it to your needs.
Feel free to share your scripts though!

When using a static IP, you may need to set the default gateway and DNS servers too, as these normally come from the DHCP server.
You may also use bonding to get a single IP valid for both network interfaces (like the WD firmware does by default). Just check the netplan.io examples.

Why CPU temps are reversed? - It’s critical when CPU temp is less than 1, it’s cool when greater than 97. Am I reading it correctly?

It compares temp delta from critical lvl of 90 degrees celsius. So when the cpu rises to 89 degrees, the delta is 1 degree and it goes into critical mode.

I think I found my problem,
Once the temperature is not within the normal CPU temp range, it keeps incremented every 10 seconds which is the default interval.

How is the reboot or shutdown working on yours? On mine, the device is not rebooting.

Do you mean the power button doesn’t work?

Power button is working, but reboot or shutdown commads are not working. after issuing these commands, I have to use power button to shutdown

So sudo poweroff or sudo halt -p doesn’t work for you? I don’t have any issues with it.
Check your /var/log/syslog and journalctl for clues…

halt -p is working, but how about “reboot”?

Sorry, I’ve been working on an other project to replace mksapkg … I’ll revisit the wdhw-tools when I’m done.
I did see a few reboot related anomalies.

How to replace your ZFS pool drives

This procedure can be used to replace faulty disks or to upgrade all your disks (one by one) to increase your zpool size. Always make a backup of your data first and consider using a UPS.

First backup your current configuration. The zdb command provides detailed info on your pool. It comes in handy when the disk is gone from your system.

zdb > media.zdb

Disable the first drive from the pool. The pool is named media. My pool does not spread over the complete disk, only he second partition of each disk is used.

zpool offline media /dev/sda2

Remove the drive from the slot and insert a new drive (with at least the same capacity).

I had to create a partition table first. I simply copied the partition table of one of the other disks (sdb) and generated new disk GUIDs. You don’t need to do this if your pool uses the complete disk.

sgdisk --replicate=/dev/sda /dev/sdb
sgdisk -G /dev/sda

Then resilver the pool with

zpool replace media /dev/sda2 /dev/sda2

Track the resilver progress with

zpool status media

It took about 15 hours for a full 4TB WD red drive.

Maybe a stupid question, but is it possible to install an OS to the first HDD? I have a bit of linux experience so it shouldn’t be a problem if it is more technical. I think I saw that you had another post regarding Debian that mentioned directly installing it to disk but I am not sure

Yes, you can burn the image to any disk and use it to boot the PRx100, wherever drive slot or usb port you plug it in.

1 Like

While I’m at it, it seems that when I specify the bios file for KVM to use it won’t boot the VM. It will if I leave it out, is there a way to fix this that you know of? And does it even matter if it boots with (I guess) another bios?

Got it working with the GUI program virtual machine manager and this guide: UEFI/OVMF - Ubuntu Wiki

1 Like