Describe Setting up Xen and XAPI (XenAPI) on Ubuntu Server 12.04 LTS and Managing it With Citrix XenCenter or OpenXenManager here.

About This Guide

This guide is intended for users who want to use XEN in a simple and uncomplicated way exploring all Ubuntu Server 12.04 LTS facilities and for users who work in hybrids environments and with "hybrids users" (Windows/Linux).

This guide is comprehensive and include installation and configuration of Ubuntu Server 12.04 LTS too. Here we present the installation of a graphical user interface (GUI) and remote desktop access, among other things.

We also had the concern to provide brief guidance (embedded on this guide) on how you can test this procedure (using VMware Workstation). Being a friendly Hypervisor, we suggest VMware Workstation as the test environment for those interested in studying and using XEN. That is, we are talking about installing XEN (XCP-XAPI) on VMWare Workstation so that the user can know the technology in a simple, controlled, fast and safe way.

We explain the installation of the OpenXenManager toolstack and present another toolstack alternatives.

I could use XenServer, right?

  • The XenCenter is a great and practical option, but in the end you will come across some problems:

    • User Interface extremely limited (pure CLI)
    • Renew License "free" every 12 months
    • You will not be using a system truly free

Hardware limitations


Xen is a type 1, bare-metal virtual machine monitor (or hypervisor), which provides the ability to run one or more operating system instances on the same physical machine. Xen, like other types of virtualization, is useful for many use cases such as server consolidation and isolation of production and development environments (Eg.: corporate and personal environments on the same system).

As of Ubuntu 11.10 (Oneiric), the default kernel included in Ubuntu can be used directly with the Xen hypervisor as the management (or control) domain (dom0 or "Domain0" in Xen terminology).

Our example uses LVM for virtual disks and network bridging for virtual network cards. It also assumes Xen 4.1 (the version available in 12.04). It assumes a familiarity with general virtualization issues, as well as with the specific Xen terminology. Please see the Xen wiki (see for more information.

During Installation of Ubuntu

  • Note: For VMware Workstation test users:
            On VM settings enable "Virtualize Intel VT-x/EPT or AMD-V/RVI"

During the install of Ubuntu for the Partitioning method choose "Guided - use the entire disk and setup LVM". Then, when prompted to enter "Amount of volume group to use for guided partitioning" enter a value large enough for the Xen dom0 system, leaving the rest for virtual disks. Enter a value smaller than the size of your installation drive. For example 100 GB should be large enough for a minimal Xen dom0 system. Keep in mind that in our model stay inside that guest (dom0) all installation media for guest OSs and other useful files, so that guest must have enough space on it.

After Installation of Ubuntu

Install GUI

sudo apt-get update
sudo apt-get install ubuntu-desktop

To skip the login screen completely, boot into the console and then start the GUI

sudo gedit /etc/default/grub


Save and exit.

sudo update-grub

Reboot and you should come up directly in tty1.

Login, and then "startx" to boot into the default desktop.

To logoff "Unity" (default Ubuntu desktop) from command line type "gnome-session-quit".

Install Windows Remote Desktop

We understand that this is the best approach to have remote access to "Ubuntu Server 12.04 LTS" into a cross-plataform environment. The "XRDP" is an implementation of the "Remote Desktop" standards from Microsoft and works on the same way as for Windows. Allows remote desktop access via native Windows client machines (or "RDESKTOP" on Ubuntu), does not require loading the "Ubuntu Server 12.04 LTS" GUI (Graphical User Interface) on boot and allows multiple simultaneous sessions. To use "RDESKTOP" on Ubuntu 12.04 LTS with "TSCLIENT" see my post on

With "XRDP" you can easily use Microsoft RDP to connect to Ubuntu without any configuration. All you need to do is install the "xrdp" package, then open Remote Desktop Connection from Windows and connect. That's it, nothing to configure.

Without wasting anymore of your time, let’s get going.

  • sudo apt-get install xrdp

Next, open Windows Remote Desktop Connection (RDP) and type Ubuntu Server hostname or IP address.

Off Course You Can Use the Great SSH

As you may already know, SSH is a secure communication protocol that lets you remotely access networked computers. It is known as a replacement for Telnet which is very unsecure. While Telnet sends traffic in plain text, SSH on the other hand uses a secure protocol to communicate.

Run the commands below to install SSH Server.

  • sudo apt-get install openssh-server

To log in on remote machine type on your terminal

  • ssh <remote_user>@<ip_or_name>

Installing Xen (XCP - Xen Cloud Platform)

XCP (Xen Cloud Platform) is the open source version similar to Citrix XenServer that uses the Xen Hypervisor. XCP uses XAPI or XenAPI to manage Xen hosts. XCP is based on CentOS 5.5.

Project Kronos is an initiative to port the XAPI tool stack to Debian and Ubuntu. It is a management stack implemented in OCaml that configures and controls Xen hosts, attached storage, networking and virtual machine life cycle. It exposes a HTTP API and provides a command line interface (xe) for resource management.

XenCenter is Windows desktop application by Citrix that is distributed with XenServer for managing servers running XenServer (the equivalent of linux is OpenXenManager). It uses XAPI for talking to Xen resource pools. Since we are setting up XAPI, we can use XenCenter to manage the server.

Why use XCP-XAPI on Debian/Ubuntu when XCP appliance exists?

  • Manage dom0 using a configuration management framework (Puppet, Chef...)
  • Apply security updates to dom0 root file system
  • Run Xen version 4.1.
  • Ubuntu Server 12.04 is a LTS release that is supported for 5 years

Installing and configuring Xen Hypervisor

  • Install the Xen Hypervisor
    • sudo apt-get install xen-hypervisor
    Setup GRUB to boot the Xen Hypervisor
    • sudo sed -i 's/GRUB_DEFAULT=.*\+/GRUB_DEFAULT="Xen 4.1-amd64"/' /etc/default/grub
    Disable apparmor at boot
    • sudo sed -i 's/GRUB_CMDLINE_LINUX=.*\+/GRUB_CMDLINE_LINUX="apparmor=0"/' /etc/default/grub

    Restrict "dom0" to 1GB of memory and 1 VCPU (example) (see "Why should I dedicate fixed amount of memory for Xen "dom0"?")

    • sudo gedit /etc/default/grub
      After GRUB_CMDLINE_LINUX="apparmor=0" add the line GRUB_CMDLINE_XEN="dom0_mem=1G,max:1G dom0_max_vcpus=1"
    Update Grub with the config changes we just made
    • sudo update-grub
    Reboot the server so that Xen boots on the server
    • sudo reboot
    Once the server is back online ensure that Xen is running
    • cat /proc/xen/capabilities should display "control_d"
      Note: To stop or start xcp-xapi
              sudo /etc/init.d/xcp-xapi stop (or start)
    Installing and configuring XAPI (XenAPI)
    • Install XCP-XAPI
      • sudo apt-get install xcp-xapi

        -> Choose "bridge" when prompted for network backend

      Setup the default toolstack
      • sudo gedit /etc/default/xen

        -> Set "TOOLSTACK=xapi"

      Disable xend from starting at boot
      • sudo sed -i -e 's/xend_start$/#xend_start/' -e 's/xend_stop$/#xend_stop/' /etc/init.d/xend

      Note: Only xend the deamon needs to be disabled from starting, "/etc/init.d/xend" handles other things like modules and xenfs. Do not disable it from the runlevel. Disable service xendomains

      • sudo update-rc.d xendomains disable
      Fix for "qemu" which emulates the console does not have the keymaps in the correct location
      • sudo mkdir /usr/share/qemu; sudo ln -s /usr/share/qemu-linaro/keymaps /usr/share/qemu/keymaps
      Network configuration
      • This section describes how to set up Linux bridging in Xen. It assumes eth0 is both your primary interface to dom0 and the interface you want your VMs to use. It also assumes that you will use manually IP configuration.
        • sudo apt-get install bridge-utils

          Note: If not already installed

        As you are working with a desktop install, disable "Network Manager"
        • sudo stop network-manager
          sudo gedit /etc/NetworkManager/NetworkManager.conf
          • Now make sure the "managed" line contains "managed=false" Save and exit
          Since Network Manager is not managing your network interfaces anymore, you must manually enter that information. Below we explain how.
        Setup bridge networking
        • sudo gedit /etc/network/interfaces
          • Create a bond called xenbr0. The file should look like this for a static network configuration:
            • # This file describes the network interfaces available on your system
              # and how to activate them. For more information, see interfaces(5).
              # The loopback network interface
              auto lo
              iface lo inet loopback
              # Xen network interface for "dom0"
              auto xenbr0
              iface xenbr0 inet static
              # IP address
              # Subnet mask
              # Default Gateway
              # DNS Server
              bridge_ports eth0
              iface eth0 inet manual
              # The primary network interface
              # auto eth0
              # iface eth0 inet dhcp
        Configure xcp to use "bridge" networking instead of "openswitch"
        • sudo gedit /etc/xcp/network.conf

          -> Replace “openswitch” with “bridge”

          Note: For VMware Workstation test users:
                  - Configure with "bridge" for network adapter and run these comands on host:
                          sudo chmod ugo+rwx /dev/vmnet0
                          sudo chown <username> /dev/vmnet0
                          sudo chown :<usergroup> /dev/vmnet0
                                  sudo chmod ugo+rwx /dev/vmnet0
                                  sudo chown eduardo /dev/vmnet0
                                  sudo chown :eduardo /dev/vmnet0
        To test whether the network is working run the command
        • sudo /etc/init.d/networking restart
      All set! Ready to reboot and let xcp-xapi toolstack take over
      • sudo reboot
      On restart confirm that xcp is working
      • sudo xe vm-list
        • This should list the control domain
          • "
            uuid (RO) : dbcf74d2-ee50-edd5-d44d-b81fc8ba1777
            name-label (RW): Control domain on host: ubuntu-xenserver-1
            power-state (RO): running

          -> If your output looks similar, "xapi" is running on the server, if you get “Connection refused” then xapi is not setup correctly!

      Configure Storage Repository for Use With XAPI
      • NFS servers are a common form of shared filesystem infrastructure, and can be used as a storage repository substrate for virtual disks. As NFS storage repositories are shared, the virtual disks stored in them allow VMs to be started on any server in a resource pool and to be migrated between them using XenMotion. When you configure an NFS storage repository, you simply provide the hostname or IP address of the NFS server and the path to a directory that will be used to contain the storage repository (if this resource is on another machine, it is not our case). The NFS server must be configured to export the specified path to all servers in the pool.

        • To show your volume group (VG)
          • sudo pvs
          Create a LV with X GBs
          • sudo lvcreate -L <X>GB -n <StorageRepositoryName> /dev/<VG>
            Eg1.: sudo lvcreate -L 25GB -n StorageRepository /dev/ubuntus1204
            Eg2.: sudo lvcreate -l 100%FREE -n StorageRepository /dev/ubuntus1204
          Register the logical volume for use with XAPI
          • sudo xe sr-create type=ext shared=true name-label=<StorageRepositoryName> device-config:device=/dev/<VG>/<StorageRepositoryName>
            Eg.: sudo xe sr-create type=ext shared=true name-label=StorageRepository device-config:device=/dev/ubuntus1204/StorageRepository
          This should display the Storage Repository
          • sudo xe sr-list name-label=<StorageRepositoryName>
            Eg.: sudo xe sr-list name-label=StorageRepository
            • "
              uuid ( RO): 37bc5263-c9fc-8876-d24c-d5927f1bbed2
              name-label ( RW): StorageRepository
              name-description ( RW):
              host ( RO): ubuntus1204
              type ( RO): ext
              content-type ( RO):
      Configure a ISO Repository for Use With XAPI
      • An ISO Repository contains ISOs (disk images) with operational systems to perform the installations.
        • Then the following example makes a storage repository called ISOs
          • sudo xe sr-create name-label=<LocalISORepositoryName> type=iso shared=true device-config:location=<FolderPath> device-config:legacy_mode=true content-type=iso
            sudo mkdir -p /var/opt/xen/LocalISORepository/
            sudo xe sr-create name-label=LocalISORepository type=iso shared=true device-config:location=/var/opt/xen/LocalISORepository/ device-config:legacy_mode=true content-type=iso
          This should display the ISO Repository
          • sudo xe sr-list name-label=<LocalISORepositoryName>
            Eg.: sudo xe sr-list name-label=LocalISORepository
            • "
              uuid ( RO): 26edb27b-72fc-af56-ad2f-4d15a8d8e3f7
              name-label ( RW): LocalISORepository
              name-description ( RW):
              host ( RO): ubuntus1204
              type ( RO): iso
              content-type ( RO): iso

Download and install XenCenter (Windows)

Go to and download the ISO "XenServer-6.1-install-cd.iso" (if the version is 6.1, of course).

  • The installer "XenCenter.msi" is inside. Note that this ISO is also the installation CD of XenCenter.

Start XenCenter and click "Add New Server". Put in the server ip, username and password as setup during installation, let the magic begin!

Download and install OpenXenManager (Alternative to XenCenter) (Ubuntu 12.04 Server LTS)

OpenXenManager is a free clone of the XenCenter and is supposed to be fully compatible with both XenServer and the freeware XCP. The program comes bundled as a bunch of Python scripts, contained in a single archive, so the deployment is a breeze pretty much everywhere. You won't get any visual integration with your desktop theme, though.

You might want to consider this program if you're going for an all-free combo setup with XCP perhaps, or if you require GUI management from Linux, as OpenXenManager does run on non-Windows machine, unlike XenCenter, which is for Windows only. Now, the official page looks a little out of date, so you might want to take long-term support into consideration, too. But enough talking, let's OpenXenManager in action.


Final Considerations

  • If you are looking for a simple, free and non-Windows GUI manager for Xen-based bare-metal hypervisor appliances, then OpenXenManager is the tool you want, despite its ugly looks and some functionality deficiency. It allows for a good pairing with XCP, countering the Citrix Server-Center solution, for a nil price tag.

    OpenXenManager gives you all the functionality the pair product does. However, I must admit that it is less robust and more prone to weird errors, especially relating to the network configuration. You will have to make sure your network does not have proxy or firewall rules that might interfere with the program's connectivity. Furthermore, it may not always work, with or without SSL tunneling. This is the risk you will have to weigh in your deployment strategy. All in all, though, it works okay.

Why should I dedicate fixed amount of memory for Xen "dom0"?

First of all (dom0) Linux kernel calculates various network related parameters based on the boot time amount of memory. The second reason is Linux needs memory to store the memory metadata (per page info structures), and this allocation is also based on the boot time amount of memory.


Setting up Xen and XAPI (XenAPI) on Ubuntu Server 12.04 LTS and Managing it With Citrix XenCenter or OpenXenManager (last edited 2013-02-26 16:07:39 by eduardolucioac)