Connect a USB drive to a LXC container in PVE

Connecting a USB drive to a LXC container expands the disk space for that container. In my case, I was able to expand a nextcloud with external space that did not need a backup.

Mount to PVE host

To connect, lets start with connecting the hardware and get the ID of it. Execute the following on your PVE host.

ls -ahlp /dev/disk/by-id

It will return something like this:

Mar 15 02:02 usb-Seagate_Basic_NT22RPD8-0:0 -> ../../sda
Mar 15 02:02 usb-Seagate_Basic_NT22RPD8-0:0-part1 -> ../../sda1

Now permanently mount the disk to a folder by creating a service and start and enabling it. Create a file:

# vim /etc/systemd/system/mnt-pve-YOURDIR.mount
[Install]
WantedBy=multi-user.target

[Mount]
Options=defaults
Type=ext4
What=/dev/disk/by-id/usb-Seagate_Basic_NT22RPD8-0:0-part1
Where=/mnt/pve/YOURDIR
[Unit]
Description=Mount storage 'YOURDIR' under /mnt/pve

Now reload the system daemon, start the service and if it succeeds, enable it to mount it at every system startup.

systemctl daemon-reload
systemctl start mnt-pve-YOURDIR.mount
systemctl enable mnt-pve-YOURDIR.mount

If everything worked, you can access your USB drive via ls /mnt/pve/YOURDIR from the PVE host.

Mount to LXC container

Access the configuration file of your LXC container and add line:

# vim /etc/pve/lxc/XXX.conf
# Add this line
lxc.mount.entry: /mnt/pve/YOURDIR path/in/container none bind,optional,create=dir

The optional enables the container to start even if the bind fails. Not the leading / in the path of the PVE folder, but the missing / in the path inside the container!

Limitation

This directly maps an external disk into a container. Note, that

1. the container can only run on the PVE host, where the disk is connected to
2. no backup via the PBS is possible that way

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Last update: 2026-03-17