How to make raw image mounting work under Ubuntu (at least on my machine)

Hi UrBackup Community,

I never got image mounting to work until tody so I decided to give those of you who are still having troubles a small guide. I haven’t found a post here that covered all the steps (though there was not much to do really).

First of all: I’m running urbackup on a ubuntu server 17.10 and I’m using btrfs for my storage with raw image files. Also urbackup server runs in the default configuration with urbackup user.

Step 1: Change permissions on kernel
sudo chmod 0644 /boot/vmlinuz* (see

Step 2: Add urbackup user to kvm group
sudo usermod -a -G kvm urbackup (see

Step 3: Mount image from CLI as root
sudo urbackup_mount_helper mount <CLIENT> <CLIENT_FOLDER> <CLIENT_IMAGE>.raw

Step 4: Unmount image from CLI as root
sudo urbackup_mount_helper umount <CLIENT> <CLIENT_FOLDER> <CLIENT_IMAGE>.raw

Step 5: Mount image from CLI as urbackup
sudo -u urbackup urbackup_mount_helper mount <CLIENT> <CLIENT_FOLDER> <CLIENT_IMAGE>.raw (see UrBackup Server 2.1.6 beta)

Step 6: Unmount image from CLI as urbackup
sudo -u urbackup urbackup_mount_helper umount <CLIENT> <CLIENT_FOLDER> <CLIENT_IMAGE>.raw

Step 7: Mount image from Web Interface

For some reason mounting as root enabled the urbackup user as well to mount images. Step 5 did produce a “supermin exited with error code 1” before that. Steps 5 and 6 are most likely not required, but thats just what I did for testing.

I will check if mounting will now also work for different images and also after a reboot. It most likely won’t work after a kernel update since the default permissions under ubuntu are too restrictive.

I hope I could help someone with this post.


1 Like

The latest version should do that automatically on Ubuntu (if it is working as intented).


just to try, in my ubuntu16.04,mount image is ok,is very very bad on centos

For some reason after a couple of restarts the mounting does no longer work. Mounting as root enables mounting via web interface again.