VMmanager 6: Administrator guide

Managing servers in the cluster

A cluster is a group of servers in a single location. The key feature of such servers (cluster nodes) is their location and high data transfer speed between them. 


You can set up your own scripts to run automatically when the server is connected to the cluster. Read more in Creating a script for the node.

Server connection


When the server connects to the LXD cluster, all information in the node's ZFS pool will be deleted.

Perform the following steps to connect a server to the cluster: 

  1. Make sure the server meets the requirements described in the article Server requirements for the cluster.
  2. Go to Cluster nodes → Connect a node.
  3. Enter a cluster node Name
  4. Enter a server IP address and Port to connect via SSH. The default port is 22. 
  5. Enter the server Root password or add a public SSH-key of the server with VMmanager. To do so, click on I want to use a public ssh-key, copy the key, and add it into the file /root/.ssh/authorized_keys on the server. 
  6. Select a Cluster that the server will be connected to.
  7. Enter the Overselling ratio. Learn more in Overselling
  8. If you are connecting the server to a cluster with IP-fabric type, specify an IPv6 address for configuring networks.
  9. If you connect the server to the cluster with the "Routing" network configuration type, enter the IP for new VM. You can enter single IP addresses, or a mask. Enter every IP address from a new line. 
  10. Enter additional information into the Notes field.
  11. Click on Connect the node.
  12. If you have selected a cluster with two network interfaces, specify the Interface for the main network and/or the Interface for the additional network. Read more in Main and additional network. Press Continue.

The system will install the required software and configure the server. 


To increase the number of possible network connections, VMmanager changes the values of net.nf_conntrack_max and net.netfilter.nf_conntrack_max parameters to 1048576 on the cluster node. Read more in How to change netfilter parameters?.

Cluster node dashboard

To see the information about the cluster node, go to Cluster nodes → open the cluster node page.

To view information on cluster nodes, go to Nodes. The following parameters are displayed in the cluster node dashboard:

  • CPU, % — CPU load;
  • RAM, % — RAM used;
  • Storage, % — HDD space used;
  • All VM — total number of VMs on the node;
  • number of VMs with a certain status;
  • Estimated number — maximum possible number of VMs. The value is calculated dynamically and depends on available node resources;
  • Cluster — cluster name;
  • OS — operating system;
  • IP-address — IP-address of the node;
  • Uptime — time of continuous node operation;
  • Services — services running.

On the scales CPU, RAM, Storage, the used amount of resource is displayed in green, and the amount of resource allocated for the VM, taking into account overselling, is displayed with an orange label.

Cluster node dashboard interface

Open cluster node page to view node details.

Change connection settings

If the IP address and/or SSH port on the cluster node has changed, VMmanager will lose connection with the node. To reconnect:

  1. Go to Nodes → select a node → MenuChange connection settings.
  2. Specify the Node IP address.
  3. Specify the SSH port.
  4. Click Connect to node.

Forbid users to create VMs on a cluster node

To prevent users from creating virtual machines on a cluster node: 

  1. Go to Cluster nodes → menu Prohibit VM creation.
  2. Click on Confirm.

To cancel the settings: 

  1. Go to Cluster nodes → menu → Allow VM creation.
  2. Click on Allow.