Raspberry Pi as a NAS Backup appliance

Raspberry Pi as a NAS Backup appliance

Raspberry Pi as a NAS Backup appliance

I needed a backup solution for my home NAS (QNAP), and preferably, it should be an offsite backup. My NAS only have one disk slot, so for obvious reasons it cannot support RAID, but even if it did support RAID, it would only protect my data from disk failure. RAID cannot protect my data from a house fire or lightning strike nor theft of the actual NAS. This would be assured by having an offsite backup. Now why did I not just use one of the could services, which already are integrated in the NAS? Well, for two reasons โ€“ First, I do not like the idea of my data stored in a cloud service, and secondly I love to play with these things. ๐Ÿ™‚

In order the keep the cost low, I choose to build the solution on a Raspberry Pi and a 2 TB USB hard drive, which is less expensive than the cheapest NAS I could find. Both my NAS and the Pi supports RSYNC, so this will be the transfer and synchronization application. The data needs to be encrypted in transit, so it can be transferred on the Internet. Rsync can use SSH to do this, but this would expose my NAS to the public internet. I could restrict the access in my firewall, but this would require the remote site to have a known static IP address. Since I will place the offsite backup at some of my relatives, this will not work, as they do not have a static IP. The encrypted access is therefore done by Remote Access VPN to my Cisco ASA firewall.


QNAP configuration

The configuration of the NAS is simple and is all done by the web interface. Logon the system, and go to Control Panel –> Applications –> Backup Server –> Rsync server.

Enable backup service and allow remote Rsync to backup data, and set the username and password which will be used for this.

Thatโ€™s it for the NAS.



Pi configuration

Basic configuration

Download the latest Raspbian distribution and write it to a SD card which does not have to very large. Boot up the Pi and run initial configuration from the wizard.

Next, update the Pi before continuing

sudo apt-get update
sudo apt-get upgrade

The network configuration are default to DHCP and I will keep it this way, since I want this solution to be flexible and moveable.

USB Drive configuration

Attach the USB Hard drive

Plug the hard drive into the Pi and verify that the Pi have found the disk



Use fdisk to partition the disk and use mkfs to format it.

sudo fdisk /dev/sda
sudo mkfs.ext4 /dev/sda1

Create a folder to mount the HDD in

sudo mkdir /mnt/USBHDD01

Find the UUID for the disk

ls -l /dev/disk/by-uuid/


Then update the /etc/fstab with the disk and mount point. I choose to NOT auto mount the disk, because when the disk is mounted it has constant activity, which wears the disk unnecessarily since it most of the time just will sit idle from a backup perspective. Another reason is that if the backup station will experience a power outage and the disk is dismounted, it will not be a problem to the file system. The backup script will just mount and dismount the disk as needed.


--- output omitted ---
UUID=f6fa5238-3055-4db7-9665-a6568f86db84 /mnt/USBHDD01 ext4 defaults,noauto 0 0

Now the disk is ready to use.

Install the Remote Access VPN client

vpnc is a CLI VPN client for โ€˜nix systems, and it is available for Raspbian. The vpnc will connect to the Cisco ASA I am using as edge firewall and form an IPsec remote access tunnel.

sudo apt-get install vpnc

The connection have to be configures before it can be used. First, make a copy of the template located in /etc/vpnc/default.conf

sudo cp /etc/vpnc/default.conf /etc/vpnc/MYVPN.conf

The content of the file will like the following โ€“ adjust for your VPN configuration

IPSec gateway vpn.xxxx.eu
IPSec secret presharepa$$w0rd
Xauth username USER
Xauth password pa$$w0rd

You can verify the VPN connection is working as expected

sudo vpnc-connect MYVPN

Disconnect with

sudo vpnc-disconnect


Install SSMTP

To make the Pi able to send emails install ssmtp.

sudo atp-get install ssmtp

Configure ssmtp to use an email account through the configuration file in /etc/ssmtp/ssmtp.conf
I have added the following to the standard configuration


When you send mails the system will use the actual username of the logged in user and the hostname of the system. This will probably no work with most email providers. This can be changed by creating an alias in the file /etc/ssmtp/revaliases. The script will run as root when scheduled, so I have created the alias for the root user account.


Backup script

I wrote a small script that puts all the pieces together. The script mounts the backup disk, brings up the VPN tunnel and uses Rsync to synchronize the backup disk with the NAS. It writes messages to the local syslog and sends an email, so I can verify that the backup has completed without errors.


# RSYNC NAS Backup script by Bo Urskov - bourskov.dk
# Feb 2015

# NAS settings
export RSYNC_PASSWORD=thisisasecret

# Write to local syslog

logger -t NAS-BACKUP started...

# Mount Backup HDD
echo Mounting Backup HDD...

if mount /mnt/USBHDD01 ; then
 echo Mounted USBHDD01...
 echo ERROR! Cannot mount backup disk!
 logger -t NAS-BACKUP ERROR! Cannot mount backup disk!
 ssmtp -F"BACKUP-PI" $MAILRCPT < /home/pi/MSG-BACKUP-ERROR.txt
 exit 1

# Get VPN connection
echo Bringing up VPN tunnel...
if vpnc-connect $VPN_GATEWAY ; then
 echo Connected...
 echo ERROR! Cannot bring tunnel up!
 logger -t NAS-BACKUP ERROR! Cannot bring tunnel up!
 ssmtp -F"BACKUP-PI" $MAILRCPT < /home/pi/MSG-BACKUP-ERROR.txt
 exit 2

# Verify connectivity to RSYNC Server
echo Verify connectivity to NAS...
if ping $RSYNC_SERVER -c 2 ; then
 echo NAS responds to pings...
 echo ERROR! No connectivity to NAS!
 logger -t NAS-BACKUP ERROR! No connectivity to NAS!
 ssmtp -F"BACKUP-PI" $MAILRCPT < /home/pi/MSG-BACKUP-ERROR.txt
 exit 3

# Do the backups

echo Syncing: tftproot
rsync -aP --delete $USERNAME@$RSYNC_SERVER::tftproot /mnt/USBHDD01/tftproot

echo Syncing: Billeder
rsync -aP --delete $USERNAME@$RSYNC_SERVER::Billeder /mnt/USBHDD01/Billeder

echo Syncing: Multimedia
rsync -aP --delete $USERNAME@$RSYNC_SERVER::Multimedia /mnt/USBHDD01/Multimedia

echo Syncing: data
rsync -aP --delete $USERNAME@$RSYNC_SERVER::data /mnt/USBHDD01/data

echo Syncing: ISO
rsync -aP --delete $USERNAME@$RSYNC_SERVER::ISO /mnt/USBHDD01/ISO

echo Syncing: Privat
rsync -aP --delete $USERNAME@$RSYNC_SERVER::Privat /mnt/USBHDD01/Privat

# Disconnect VPN connection
echo Disconnecting VPN...

# Wait a few secs before dismounting backup disk
echo Waiting 2 seconds before dismounting backup disk...
sleep 2

# Dismount Backup HDD
if umount /mnt/USBHDD01 ; then
 echo Dismounted USBHDD01...
 echo ERROR!
 logger -t NAS-BACKUP ERROR! Cannot dismount disk
 exit 2

# Backup completed
logger -t NAS-BACKUP Backup completed
ssmtp -F"BACKUP-PI" $MAILRCPT < /home/pi/MSG-BACKUP-OK.txt


Schedule the backup task

The last thing is to schedule the backup job in cron. The script will run as root, so I just edited the file /etc/crontab and scheduled it to run every night.

# m h dom mon dow user	command
0 0 * * * root /home/pi/nas-backup.sh


All in all, a neat and cheap solution for offsite backup of my QNAP NAS… ๐Ÿ™‚


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