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disk_usage.rst

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Disk usage

NethServer 8 uses Podman to manage OCI containers.

  • Rootless applications require the most space. They put their data inside the user's home directory, for example /home/loki1/.local/share/containers/storage.
  • Rootful applications typically store images and volumes in the /var/lib/containers/storage directory.

Inspect the default directories used by Podman with commands like:

podman info -f json | jq -r '.store.graphRoot'
podman info -f json | jq -r '.store.volumePath'

For rootless applications, prepend runagent -m <module_id>, e.g.:

runagent -m loki1 podman info -f json | jq -r '.store.graphRoot'
runagent -m loki1 podman info -f json | jq -r '.store.volumePath'

To get a list of the applications running on the local node, run:

runagent -l

There is another growing directory, /var/lib/nethserver, that contains the actions and state data of rootful modules, and core components like the user interface code. Space requirements for this directory should be minimal.

When NS8 runs multiple applications, disk usage increases rapidly, and you may run out of space. If disk space runs low, consider expanding the filesystem using the methods described in the following sections.

Expand the filesystem with external tools

As a general approach, to expand a filesystem, you have to grow the device where it is mounted first.

Often, the device itself is contained by some other device, logical or physical, like a logical volume or a disk partition. In this case, the logical volume or disk partition has to be grown.

On a physical machine, the best option is to set up LVM during the distribution installation. LVM helps with device management, and there are plenty of how-to guides that explain how to achieve this goal.

On a virtual machine, you can easily expand the entire root disk and filesystem. If you created the VM with the pre-built image, read the next section for detailed commands.

Expand pre-built image filesystem

If NS8 was installed as a virtual machine starting from the :ref:`pre-built image <install_image-section>` in QCOW2 format, follow this procedure.

  1. Shut down the node and resize its .qcow2 image from its host system. For example

    sudo qemu-img resize ns8-disk.qcow2 +50G

  2. Start the node and grow its 5th partition (remove the --dry-run option, when you are confident):

    growpart --dry-run /dev/vda 5

  3. Grow the root filesystem:

    xfs_growfs /

Attach a disk for new applications

At any time in the NS8 node's life, you can mount a new disk on an alternative path, like /home1, and start to install applications on it. Existing rootless applications will continue to use their home directory on the old disk, whilst new apps will be created under /home1 and consume the new disk space.

  1. Create the alternative base path:

    mkdir -m 0755 /home1

  2. Mount the device on the new path:

    mount /dev/some /home1

    To persist the mount, edit /etc/fstab or create a systemd .mount unit. Verify that the device remains mounted after a reboot.

  3. Configure the node agent to use /home1 as the base directory for new applications:

    runagent -m node configure-home-basedir --set /home1

Migrate /home data to a new disk

If the previous section is not applicable, consider adding a new disk and migrating existing data with a Bash script included in the core: migrate-home-disk.sh. This script illustrates the basic steps required for data migration.

Warning

The included script is just an example that may not fit your system. USE AT YOUR OWN RISK!

The script will:

  • stop all rootless applications
  • copy all rootless applications inside the new disk
  • reclaim space from the root filesystem
  • mount the new disk under /home
  • restart all rootless applications

Before running the script, make sure to attach the disk to the node, format it, and mount it to a custom location like /mnt/temp_disk.

Then launch the Bash script by passing the mount location as a parameter, like:

bash /var/lib/nethserver/node/migrate-home-disk.sh /mnt/temp_disk