5.11. Corosync Configuration

The /etc/pve/corosync.conf file plays a central role in a Proxmox VE cluster. It controls the cluster membership and its network. For further information about it, check the corosync.conf man page:

man corosync.conf

For node membership, you should always use the pvecm tool provided by Proxmox VE. You may have to edit the configuration file manually for other changes. Here are a few best practice tips for doing this.

Editing the corosync.conf file is not always very straightforward. There are two on each cluster node, one in /etc/pve/corosync.conf and the other in /etc/corosync/corosync.conf. Editing the one in our cluster file system will propagate the changes to the local one, but not vice versa.

The configuration will get updated automatically, as soon as the file changes. This means that changes which can be integrated in a running corosync will take effect immediately. Thus, you should always make a copy and edit that instead, to avoid triggering unintended changes when saving the file while editing.

cp /etc/pve/corosync.conf /etc/pve/corosync.conf.new

Then, open the config file with your favorite editor, such as nano or vim.tiny, which come pre-installed on every Proxmox VE node.

After making the necessary changes, create another copy of the current working configuration file. This serves as a backup if the new configuration fails to apply or causes other issues.

cp /etc/pve/corosync.conf /etc/pve/corosync.conf.bak

Then replace the old configuration file with the new one:

mv /etc/pve/corosync.conf.new /etc/pve/corosync.conf

You can check if the changes could be applied automatically, using the following commands:

systemctl status corosync
journalctl -b -u corosync

If the changes could not be applied automatically, you may have to restart the corosync service via:

systemctl restart corosync

On errors, check the troubleshooting section below.