Xen4 CentOS6 QuickStart
This guide will help you get from a baseline CentOS-6/x86_64 install to running the complete Xen-4 stack in just under 10 minutes, this includes getting your first VM up.
Xen-4.4 and libxl
We assume you already have a fair idea of virtualisation, the difference between para-virt (pv) and fullvirt (hvm) and have a basic understanding of how networking on linux works, including bridge utils.
Read the Release Notes at http://wiki.centos.org/Manuals/ReleaseNotes/Xen4-01 ; they cover important notes, known issues, workarounds and details on where to get help, should you need it.
- The machine hosting the Xen hypervisor should be a CentOS-6/x86_64 minimal install; before going any further, you should ensure that only the CentOS repos are enabled for yum, and that you have the latest updates applied. The Xen4 stack for CentOS has only been tested and verified on CentOS-6.4 and newer.
- We assume that the machine has 1.5GB or more RAM and more than 10GB of disk space for the root filesystem under /
Install the Xen4CentOS Stack
The software released for this stack is hosted in its own self contained repository on the CentOS mirror network. In order to enable this repository, ensure that the CentOS-Extras repo is enabled and type:
yum install centos-release-xen
Once that is done, we can now install xen itself:
yum install xen
The Xen hypervisor runs above the linux kernel, and we need to tell grub to boot it first and then chain boot the linux kernel for our dom0. In order to do that, a script is provided as part of the centos-release-xen rpm, lets run that now:
At this point if you look at your /boot/grub/grub.conf it should have something like this:
title CentOS (3.4.46-8.el6.centos.alt.x86_64) root (hd0,0) kernel /xen.gz dom0_mem=1024M,max:1024M loglvl=all guest_loglvl=all module /vmlinuz-3.4.46-8.el6.centos.alt.x86_64 ro root=/dev/mapper/vg_xen01-lv_root rd_LVM_LV=vg_xen01/lv_swap rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=uk rd_NO_MD LANG=en_GB rd_LVM_LV=vg_xen01/lv_root SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_NO_DM rhgb quiet module /initramfs-3.4.46-8.el6.centos.alt.x86_64.img
and this should be set as your default boot kernel. Once you reboot, verify that the 3.x kernel is running with:
and verify that xen is running with:
NOTE: There is a ballooning bug that causes a error log entry as described in Bug 6893, so dom0_mem=1024M,max:1536M would get rid of that error message.
Bringing up the first VM
At this point you are now ready to bring up your first VM, and there are multiple ways of achieving this. For new users, who are looking for the easiest install path, the Libvirt process is recommended. Advanced users looking to hand setup the network, the backing filestore and the xen environment will most likely want to use the xen command line tools.
With Xen CLI tools, including xm and xl: /Xen4Cli
Using LibVirt/ Virt-install and Virt-Manager with xen4centos: /Xen4Libvirt