A cluster is a group of modes where virtual machines run. Cluster nodes are physical servers. Before you add them into the cluster, you need to perform some configuration. 

This article describes the requirements that must be met by the servers you want to use as cluster nodes.

System requirements

Supported operating systems:

  • CentOS 7 x64 (recommended).

Note

You should install a minimal version of the operating system.

We don't recommend that you update the operating system of cluster node with major version changing.

Be sure to install the operating system of the same version on all cluster nodes. The control panel won't allow adding a cluster node if its operating system differs from the one installed on VMmanager server. For example, you cannot add a cluster node with CentOS 7.6, if the master server runs on CentOS 7.5.

Network requirements


  • All cluster nodes must be in the same network;
  • SSH must listen on the port 22 on every node;
  • you can allocate 100-150 Gb for the root partition;
  • disable protection from multicast storm;  Make sure that "igmp snooping" is disabled on the switch connected to the server. This option activates the protocol that blocks multicast;
  • all server must have at least two Ethernet-connections. Configure the public IP on one of them and the internal network on the other. The network must be included in one VLAN;
  • pay attention to the network bandwidth when you set up network storages;   
  • VMmanager Cloud can run on any cluster node and the license IP address will move from one node to another with the control panel. We recommend that you assign a public IP address on the master server for the license, and use the primary static IP for server management.  When you activate the cloud functions, you may not use the static IP address so it won't be added to the server network interface. To do so, delete the information about the IP from /etc/sysconfig/network-scripts/ifcfg-<interface> (CentOS).

Firewall configuration

Allow incoming connections for the following ports:

  • 22/tcp - SSH service, from all cluster nodes, and from the public network if needed
  • 111/tcp - rpcbind for NFS, from all cluster nodes
  • 662/tcp,udp - pftp for NFS, from all cluster nodes
  • 892/tcp,udp - NFS, from all cluster nodes
  • 1500/tcp - ihttpd, to access to the control panel web-interface from the public network and access the panel services on a cluster node
  • 1515/tcp - vmwatch-master monitoring of a VM state, from all cluster nodes on the server with the control panel
  • 2049/tcp,udp - NFS, from all cluster nodes
  • 32803/tcp - NFS, from all cluster nodes
  • 32769/udp - NFS, from all cluster nodes
  • 5900-6900/tcp - QEMU VNC. If access to VNC can be performed only via the control panel, the range of ports must be allowed for the network combining cluster nodes
  • 15900-16900/tcp - websockify, QEMU VNC broadcast for noVNC web interface, access from the public network
  • 49152-49261/tcp - libvirt libvirt migration services. 
  • 5404-5405/udp — corosync multicast, from all cluster nodes. May vary depending on the configuration of the cloud functions in the control panel; 
  • 21064/tcp — dlm, from all cluster nodes;
  • 41966-41969/tcp — rgmanager, all cluster nodes;
  • 50006-50009/tcp — ccsd, all cluster nodes;
  • 50007/udp — ccsd, all cluster nodes.

Recommended configuration of the disk subsystem


When installing an operating system on cluster nodes we recommend using XFS as the file system.

OS templates that VMmanager uses for guest OS are about 80 Gb (the largest templates are Windows - 10-15 GB each template. Every Unix template requires about 100 MB). Templates are located in the /nfsshare/ directory, which is duplicated to each cluster node. Allocate 60-80 Gb of disk space to /nfsshare. If you are planning to install Windows on guest systems or create custom OS templates, you may allocate less space to the partition.

If you plan to make backup copies, make sure you have in the root section has additional free space: 2,5*<maximum size of vm disk>.

Therefore, we recommend that you allocate 100-150 GB (+ some space for backup copied) for the root partition. The rest of HDD — for /vm, if you are going to use a local file system as a storage, or for the linux-lvm partition if you use a local LVM as a storage.