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How to Load DRBD on Talos Linux

This guide shows you how to set the DRBD® Module Loader when using Talos Linux.

To complete this guide, you should be familiar with:

  • editing LinstorSatelliteConfiguration resources.
  • using the talosctl command line to to access Talos Linux nodes.
  • using the kubectl command line tool to access the Kubernetes cluster.

Configure Talos system extension for DRBD

By default, the DRBD Module Loader will try to find the necessary header files to build DRBD from source on the host system. In Talos Linux these header files are not included in the host system. Instead, the Kernel modules is packed into a system extension.

Ensure Talos has the correct drbd system extension loaded for the running Kernel.

This is done by building a install image from the talos factory with drbd included

You will also need to update the machine config to set the following kernel module parameters:

machine:
  kernel:
    modules:
      - name: drbd
        parameters:
          - usermode_helper=disabled
      - name: drbd_transport_tcp

Validate drbd module is loaded: 

$ talosctl -n <NODE_IP> read /proc/modules
drbd_transport_tcp 28672 - - Live 0xffffffffc046c000 (O)
drbd 643072 - - Live 0xffffffffc03b9000 (O)

Validate drbd module parameter usermode_helper is set to disabled: 

$ talosctl -n <NODE_IP> read /sys/module/drbd/parameters/usermode_helper
disabled

Configure the DRBD Module Loader

To change the DRBD Module Loader, so that it uses the modules provided by system extension, apply the following LinstorSatelliteConfiguration:

apiVersion: piraeus.io/v1
kind: LinstorSatelliteConfiguration
metadata:
  name: talos-loader-override
spec:
  podTemplate:
    spec:
      initContainers:
        - name: drbd-shutdown-guard
          $patch: delete
        - name: drbd-module-loader
          $patch: delete
      volumes:
        - name: run-systemd-system
          $patch: delete
        - name: run-drbd-shutdown-guard
          $patch: delete
        - name: systemd-bus-socket
          $patch: delete
        - name: lib-modules
          $patch: delete
        - name: usr-src
          $patch: delete
        - name: etc-lvm-backup
          hostPath:
            path: /var/etc/lvm/backup
            type: DirectoryOrCreate
        - name: etc-lvm-archive
          hostPath:
            path: /var/etc/lvm/archive
            type: DirectoryOrCreate

Explanation:

  • /etc/lvm/* is read-only in Talos and therefore can't be used. Let's use /var/etc/lvm/* instead.
  • Talos does not ship with Systemd, so everything Systemd related needs to be removed
  • /usr/lib/modules and /usr/src are not needed as the Kernel module is already compiled and needs just to be used.