VMmanager 6: Administrator guide

If the cluster node is unavailable

VMmanager sets the "Unavailable" status for a cluster node if:

  • the node cannot be accessed via SSH;
  • libvirt software on the node cannot be accessed.

To restore access, connect to the node manually and fix the malfunction cause.

If the node cannot be accessed via SSH


  1. Check that the cluster node is available in the network of the server with VMmanager.
  2. Check that the SSH key used for connection is correct:
    1. View the content of the open SSH key on the server with VMmanager:
      docker exec -it vm_box cat /opt/ispsystem/vm/etc/.ssh/vmmgr.1.pub
    2. Check if the SSH key from the command response is contained in the root/.ssh/autorized_key file on the cluster node.  If necessary, add the SSH key to that file.

  3. Check if incoming SSH connections are enabled on the cluster node:

    lsof -i | grep :ssh
  4. Check that the number of connections via SSH on the cluster node is within limit:

    cat /etc/ssh/sshd_config | grep maxSessions

If libvirt software on the node cannot be accessed


  1. Check that the cluster node is available in the network of the server with VMmanager.
  2. Check if libvirtd service is running on the cluster node:

    service libvirtd status

    If necessary, start the service:

    service libvirtd start
  3. Check if the TLS port — 16514/tcp: is open on the cluster node:

    firewall-cmd --list-ports

    If necessary, open the port:

    firewall-cmd --permanent --add-port=16514/tcp && firewall-cmd --reload