Clone KVM-based Virtual Machines on Redhat / CentOS Linux

Prerequisite: Operating System and Software Versions

  • Operating System: – Redhat 7.3
  • Software: – libvirtd (libvirt) 2.0.0

Obtain Source Virtual Machine’s information

Before we begin cloning any virtual machine we first need to obtain some basic information about it. The absolute minimum information required about the source virtual machine we are about to clone would be its name and number of disk in use. To get virtual machines name run:

# virsh list
Id Name State
1 server1.local running

Next, we may would like to know the number of disk our source virtual machines is using as well as its location. The information about disks location is optional as it only provides us with a hint on where to store new clone disk files for the sake of consistency: # virsh dumpxml server1.local | grep "source file"
<source file='/var/lib/libvirt/images/server1.local.qcow2'/>
<source file='/var/lib/libvirt/images/server1.local-1.qcow2'/>
<source file='/var/lib/libvirt/images/server1.local-2.qcow2'/>

From the above output we can see that our original virtual machine has three disks stored in location /var/lib/libvirt/images/. Continue reading “Clone KVM-based Virtual Machines on Redhat / CentOS Linux” »


Reinstall VirtualBox on Ubuntu & CentOS

For Ubuntu

To remove virtualbox

sudo dpkg --list virtualbox-*
sudo apt autoremove --purge virtualbox*
dpkg -l virtualbox* | grep ^i

Remove all PPAs from sources.list and source.list.d directory

mkdir ~/apt-tmp
sudo mv /etc/apt/sources.list.d/* ~/apt-tmp

Make sure there is nothing except official repositories sources in /etc/sources.list. And update your sources:

sudo apt update

Now we can search to see which versions are available to install:

apt-cache madison virtualbox | grep -iv sources

Which produces an output like this:

virtualbox | 5.0.32-dfsg-0ubuntu1.16.04.2 | xenial-updates/multiverse amd64 Packages
virtualbox | 5.0.18-dfsg-2build1 | xenial/multiverse amd64 Packages

Then I would install the last version mentioned in xenial-updates: Continue reading “Reinstall VirtualBox on Ubuntu & CentOS” »


Install Qemu Guest Agent on Proxmox

The qemu-guest-agent is a helper daemon, which is installed in the guest. It is used to exchange information between the host and guest, and to execute command in the guest.

In Proxmox VE, the qemu-guest-agent is used for mainly two things:

  • To properly shutdown the guest, instead of relying on ACPI commands or windows policies
  • To freeze the guest file system when making a backup (on windows, use the volume shadow copy service VSS).

Installation Host
You have to enable the guest-agent per VM, either set it in the GUI to “Yes” under options (see screenshot):

or via CLI:

qm set VMID --agent 1

Guest Linux
On Linux you have to simply install the qemu-guest-agent, please refer to the documentation of your system.

We show here the commands for Debian/Ubuntu and Redhat based systems:

Continue reading “Install Qemu Guest Agent on Proxmox” »


Install Proxmox VE 6 on Debian 10 (Buster)

Proxmox Virtual Environment (VE) is an enterprise-grade open-source server virtualization solution based on Debian Linux distribution with a modified Ubuntu LTS kernel. It allows you to deploy and manage both virtual machines and containers.

This setup presumes you have a running Debian 10 Buster Linux server running. If you don’t have one, follow our guide to Install Debian 10 on a dedicated server that will be used as a hypervisor. Please note that you need a 64-bit processor with support for the Intel 64 or AMD64 CPU extensions.

Below are the steps you’ll follow through to install Proxmox VE 6 on Debian 10 (Buster).

Step 1: Update Debian OS

Update apt package index before getting started.

sudo apt -y update
sudo apt -y upgrade
sudo reboot

Step 2: Set system hostname

We need to set the hostname and make sure it is resolvable via /etc/hosts.

sudo hostnamectl set-hostname --static
echo " prox6node01" | sudo tee -a /etc/hosts should be replaced with a valid domain name. Continue reading “Install Proxmox VE 6 on Debian 10 (Buster)” »


Resizing a VirtualBox Virtual Hard Disk

Before you start this procedure you’ll need to do the following.

  • Make sure you have the VBoxManage command-line tool installed on your host system.
  • Download the ISO for a GParted Live CD or else a Linux Live CD using a Linux distribution that includes the GParted partition editor utility.
  • IMPORTANT: If the virtual disk you want to resize is attached to a virtual machine with snapshots, you will need to delete these snapshots so that all disk state information is merged into the base virtual disk VDI file.
  • Resize the virtual disk (VirtualBox version 4.0+ only)
    If you are using VirtualBox version 4.0 or later, you can resize the logical capacity of a virtual disk using the VBoxManage modifyhd –resize command.

On the host system, run the following command:

cd /path/to/vbox/disks
VBoxManage modifyhd OldDisk.vdi –-resize 30000

where OldDisk.vdi is the filename of the virtual disk VDI file you want enlarge and 30000 is the new maximum size (in megabytes) of the virtual disk.

If your host OS is Windows, then the commands you need to enter at the Command Prompt will look more like the following. Continue reading “Resizing a VirtualBox Virtual Hard Disk” »


Install VirtualBox on Centos 6 / 7

Step 1 – Add Required Yum Repositories

Firstly you are required to add VirtualBox yum repository in your system. Download repository file from its official site and place it under at /etc/yum.repos.d/virtualbox.repo .First navigate to /etc/yum.repos.d/ directory and use one of below commands as per your operating system.

cd /etc/yum.repos.d/

The CentOS and RedHat users also required to add EPEL yum repository using one of the following commands.

### On CentOS/RHEL 7 ### 
rpm -Uvh
### On CentOS/RHEL 6 ### 
rpm -Uvh

Step 2 – Install Required Packages

Before installing VirtualBox make sure to install all required packages to run VirtualBox like kernel-headers, kernel-devels etc. Use the following command to install the required packages. Continue reading “Install VirtualBox on Centos 6 / 7” »


Converting OVA for use with KVM / QCOW2

The OVA file is nothing more than a TAR archive, containing the .OVF and .VMDK files. Easy!

Using Evergreen ILS for example:

~ $ file Evergreen_trunk_Squeeze.ova

Evergreen_trunk_Squeeze.ova: POSIX tar archive (GNU). I’ts possible to use the tar command to list the contents

~ $ tar -tf Evergreen_trunk_Squeeze.ova 

Simply extract those things…

~ $ tar -xvf Evergreen_trunk_Squeeze.ova

Continue reading “Converting OVA for use with KVM / QCOW2” »


Install Proxmox VE on Debian 9 – Stretch

The installation of a supported Proxmox VE server should be done via Bare-metal_ISO_Installer. In some case it makes sense to install Proxmox VE on top of a running Debian Stretch 64-bit, especially if you want a custom partition layout. For this HowTO the following Debian Stretch ISO was used:

Install a standard Debian Stretch (amd64)

Install a standard Debian Stretch, for details see Debian, and select a fixed IP. It is recommended to only install the “standard” package selection and nothing else, as Proxmox VE brings its own packages for qemu, lxc.

Add an /etc/hosts entry for your IP address
Please make sure that your hostname is resolvable via /etc/hosts, i.e you need an entry in /etc/hosts which assigns an IPv4 address to that hostname.

Note: Make sure that no IPv6 address for your hostname is specified in `/etc/hosts`

For instance if your IP address is, and your hostname prox4m1, then your /etc/hosts file should look like: Continue reading “Install Proxmox VE on Debian 9 – Stretch” »


Proxmox User Management- Proxmox VE authentication server

Command Line Tool

Most users will simply use the GUI to manage users. But there is also a full featured command line tool called pveum (short for “Proxmox VE User Manager”). Please note that all Proxmox VE command line tools are wrappers around the API, so you can also access those function through the REST API.
Here are some simple usage examples. To show help type:


or (to show detailed help about a specific command)

pveum help useradd

Create a new user:

pveum useradd testuser@pve -comment "Just a test"

Set or Change the password (not all realms support that):

pveum passwd testuser@pve

Disable a user:

pveum usermod testuser@pve -enable 0

Create a new group: Continue reading “Proxmox User Management- Proxmox VE authentication server” »