Step-by-Step Guide to Installing Xen Virtualization on CentOS 6

Installing Xen Virtualization on CentOS 6

Since Red Hat stopped native Xen support from RHEL 6 and moved to KVM, many administrators still prefer Xen for its stability. This guide uses the third‑party Xen Made Easy repository to install Xen 4 on CentOS 6.6.

1. Environment

Hardware: HP DL360 G6 (E5520, 16 GB, 2×146 GB). System version: CentOS‑6.6‑x86_64‑minimal.iso

2. System Initialization

wget http://blog.linuxeye.com/lnmp-full.tar.gz
tar xzf lnmp-full.tar.gz
cd lnmp
./install.sh   # choose "no" for all prompts
chkconfig iptables off   # disable iptables

3. Install bridge-utils

yum -y install bridge-utils

4. Add the crc.id.au repository

yum -y install http://au1.mirror.crc.au/repo/el6/x86_64/kernel-xen-release-6-7.noarch.rpm

5. Install Xen hypervisor

yum -y install xen
ls -l /boot/xen.gz

6. Install Xen kernel

yum -y install kernel-xen

Note: kernel‑xen depends on kernel‑xen‑firmware; because the packages are large, it is recommended to download them locally and install with yum -y localinstall kernel‑xen*.

7. Configure GRUB

Edit /boot/grub/grub.conf to boot the Xen kernel (see screenshot).

8. Enable Xen daemon

chkconfig xend on   # enable xend at boot

9. Configure bridge networking

Create /etc/sysconfig/network-scripts/ifcfg-xenbr0 with the following content:

DEVICE=xenbr0
TYPE=Bridge
ONBOOT=yes
DELAY=0
NM_CONTROLLED=no
BOOTPROTO=static
IPADDR=192.168.3.20
NETMASK=255.255.255.0
GATEWAY=192.168.3.1

Modify /etc/sysconfig/network-scripts/ifcfg-eth0 to attach it to the bridge:

DEVICE=eth0
HWADDR=F4:CE:46:85:64:34
TYPE=Ethernet
ONBOOT=yes
BRIDGE=xenbr0
NM_CONTROLLED=no

service network restart   # restart networking

10. Reboot the server

After reboot, the system should start with the Xen kernel (see screenshot).

11. Install virtualization management tools

yum -y install libvirt

Libvirt provides a hypervisor‑agnostic API for securely managing guest operating systems. It was originally designed for Xen and later extended to support multiple hypervisors.

service libvirtd start
yum -y install python-virtinst

The python-virtinst package supplies commands such as virt-install and virt-clone for creating and cloning VMs.

12. Configure installation source

Mount the CentOS‑6.6 ISO on a web server (e.g., 192.168.3.10:81) and copy its contents to /var/www/html/centos6.6 so that other hosts can access it via http://192.168.3.10:81/centos6.6. Ensure the .treeinfo file contains the following section:

[images-xen]
kernel = images/pxeboot/vmlinuz
initrd = images/pxeboot/initrd.img

13. Install a guest OS via the console

mkdir -p /data/xen
virt-install -n vm21 -r 2048 --vcpus=2 --nographic \
  --disk path=/data/xen/vm21.img,size=20 \
  --location http://192.168.3.10:81/centos6.6 \
  --bridge=xenbr0,model=virtio

Key virt-install options:

-n, --name            Guest VM name
-r, --ram             Memory size (MB)
--uuid                Guest UUID
--vcpus=NUM          Number of virtual CPUs
--hvm                Full virtualization
--paravirt           Paravirtualization
--location=PATH      Installation source (local or URL)
--vnc                Enable VNC console
--cdrom=DEVICE       CD‑ROM installation media
--file=PATH          Disk image file
--disk=OPTIONS       Disk configuration

14. Clone the VM

virt-clone -o vm21 -n vm22 -f /data/xen/vm22.img

After cloning, start the new VM with virsh start vm22.