How is Live Migration of running VMs working?

eEVOS helps you to migrate running virtual machines from one cluster node to another one without downtime.

VM will keep its connections, RAM and all settings will be moved. Whole migration takes just several seconds.

It is very useful functionality if you wish to shut down or reboot one of the nodes for maintenance or upgrade.

What is “Network Ping Test IP”?

During the cluster creation process, you will be asked for a “Network Test IP Address.” Both servers will use this IP address to check if the network is still available. Both servers will regularly ping this IP address.

It is strongly recommended to enter multiple IP addresses there. These can be the IP addresses of your router, gateway, mail server, network printer, etc. By including multiple IP addresses, you enhance the reliability of network monitoring in the cluster, ensuring that the network is functioning properly.

Supported Guest Operating Systems

Following operating systems are supported and can be run as virtual machines (VMs) within euroNAS Enterprise Virtualisation OS (64-Bit versions only).

Microsoft Windows

In order to achieve the best possible performance Microsoft operating system require an additional paravirtualized driver to be installed during installation. Please click here for detailed instructions.

Guest OS Hardware acceleration Paravirtualized driver
Microsoft Windows Server 2022
Microsoft Windows Server 2019
Microsoft Windows Server 2016
Microsoft Windows Server 2012 R2
Microsoft Windows Server 2012
Microsoft Windows Server 2008 R2
Microsoft Windows Server 2008
Microsoft Windows 10
Microsoft Windows 8.1
Microsoft Windows 8
Microsoft Windows 7


Guest OS Hardware acceleration Paravirtualized driver
HA Cluster
Premium Ultra


Following Linux based operating systems have been certified and work “out of the box” (drivers are built-in)

Guest OS Hardware acceleration Paravirtualized driver
Rocky Linux (alle Versionen)
Red Hat Enterprise Linux 9.x
Red Hat Enterprise Linux 8.x
Red Hat Enterprise Linux 7.x
Red Hat Enterprise Linux 6.x
CentOS 7.x
CentOS 6.x
Fedora Server 23
Fedora Workstation 23
Debian Bullseye
Debian Jessie
Debian Wheezy
Ubuntu Server 14.04 LTS
Ubuntu Server 18.04 LTS
Ubuntu Server 20.04.1 LTS
Ubuntu Desktop 14.04 LTS
Ubuntu Desktop 15.10
Ubuntu Desktop 18
Ubuntu Desktop 20.04.1 LTS

Installing the paravirtual drivers

The most modern Linux Distributions have already embedded paravirtual drivers. Those are ensuring the best possible performance and communication with the host OS. For Microsoft Windows Systems this drivers must be added during the installation.

This article describes the installation within Windows Server 2012, other versions are very similar.

Following drivers must be installed:
- Memory driver - Disk driver - Network driver - VSS Communication port (important for the live snapshots)

1. After creation of the Windows VM the installation will begin. Initially no installation drives will be listed before you install the driver manually.

Select the Option Load Driver

2. Select browse

3. Select CD Drive Virtual Drivers

4. Select the folder Disk Driver and the subfolder for your windows version.
For example 2k8 = Windows 2008

5. Your virtual disk will be now shown properly and you can continue with the installation. After the installation of the OS you can install the other drivers within the device manager.(check #6)

6. After the successful installation please go to Device Manager and install the remaining drivers.

Ethernet=Network Driver PCI Device=Memory Driver PCI Simple Communications Controller = VSS Communication driver

Click with the right mouse button and select Update Driver Software ...

7. Select Browse my computer for driver software.

8. Select the folder that contains the driver (here for example network driver) and your windows version.

For example 2k8 = Windows 2008

9. Select install

10. Repeat the procedure for all remaining devices

Virtual Network for the virtual machines

Virtual Machines can use 2 different types of virtual Network.

You can create several virtual networks and also assign them to different virtual network ports.


Bridge is directly attached to one or several network ports. Through the bridge the virtual machines will get the direct access to the network.


This mode creates a virtual network that will capsule virtual machines into their own virtual network. They will communicate with each other and also have access to the outside world

NAT network can also provide a DHCP services for the VMs

On VM creation or edit you can then assign the networks to individual NICs.

How is eEVOS Plus licensed?

eEVOS Plus is licensed per CPU (unlimited cores).

Smallest license would be 1 CPU which allows installation on one server.

For the high availability at least 2 CPU licenses are required (one CPU per node).

Licenses must be kept in pairs and the amount of the CPUs must be the same on each individual node.

4 CPU license allows either 4 CPU single server or 2 Servers with 2 CPUs.

You can use motherboard with several CPU sockets – as long as these are not populated you will not be asked for additional license. This way you can later install additional CPUs and upgrade your license.

Can I assign more than one virtual network to individual VM?

On VM creation or edit you can assign different networks to each individual virtual NIC.

My OS is not on the compatibility list

eEVOS compatibility list contains the list of all tested and certified operating systems

However there is a wide range of compatible operating systems not mentioned on our list. For the installation of these operating systems please choose during the install the option “other” – you will get following modes

Virtio Mode

Virtio Mode uses paravirtualized drivers providing best performance – it is already embedded in the most modern Linux Distributions (for not listed windows versions please use compatibility mode or test it with some other windows version listed during the VM creation).

Compatibility Mode

This mode emulates standard hardware which most operating systems support “out of the box”. For example “Intel Gigabit Network Controller”.

VM-Backup – which restore options are possible?

The VMs can be recovered quickly and easily. The recovery can be performed on any eEVOS server.
There are different types of restore depending on your requirements

New VM

This option is offered automatically if there is no virtual machine with this name on the eEVOS Server.
During recovery, it will automatically create new VM on the drive of your choice.
This option should be used when recovering on a new system or migrating VMs.


When restoring to a snapshot, the restored VM will be shown in the snapshot management of the VM. You can then use the option “recover from snapshot” to set this VM online and replace existing running VM.
Another advantage is that it will restore the memory of your backup as well so you will get the same state of the running system as it was during the backup.

Replace existing VM

The existing VM is restored from the backup and completely replaced

New VM-Clone

Instead of replacing the existing VM you can create a new VM from the backup that will have a new name. In order to avoid conflicts, it will automatically change the MAC address of the virtual network cards.

Can I restore VM-Backup to any eEVOS installation

Yes – eEVOS backup are idependent from the installation.

You can restore it on to a completely different eEVOS installation. You should only keep in mind that the new installation either has equal hardware or you need to edit the VM configuration before you start the VM.

For example:

Your VM was running in a dual CPU configuration with 6 cores. New system has only one CPU with 4 cores. Before starting the VM – go under “Edit” and change the CPU settings. Same for Memory, network etc.