For a long time I have tested many different virtualization techniques; Xen, VMWare, and Microsoft VM. Until now I’m able to conclude that all of them are usable on my desktop machine, but bothVMWare and Microsoft’s VM are more sluggish that Xen. This weekend I deployed my first server based on the upcoming Debian Etch andXen. Everything worked out of the box.
Here is what I did to install Xen on Debian Etch:
sudo apt-get install xen-linux-system-2.6.18-4-xen-686 libc6-xen bridge-utils
Boot into the newly installed Xen enabled Linux kernel
sudo reboot
Then adjusted the network settings in /etc/xen/xend-config.sxp. Enabling the network bridge:
(network-script network-bridge)
Install xen-tools:
apt-get install xen-tools
Xen tools is a collection package containing different tools related to Xen, a virtual machine creator etc.
Edit adjust the kernel and initrd parameters in /etc/xen-tools/xen-tools.conf to match the ones on your system:
Find out what the kernel image and initrd is named by:
ls /boot/vmlinuz*
/boot/vmlinuz-2.6.18-4-686 /boot/vmlinuz-2.6.18-4-xen-686
and
ls /boot/initrd*
/boot/initrd.img-2.6.18-4-686 /boot/initrd.img-2.6.18-4-686.bak /boot/initrd.img-2.6.18-4-xen-686
Adjust the lines
#
# Default kernel and ramdisk to use for the virtual servers
#
kernel = /boot/vmlinuz-2.6.18-4-xen-686
initrd = /boot/initrd.img-2.6.18-4-xen-686
Further adjust the xen-tools.conf to this settings:
dir = /home/xen
debootstrap = 1
size = 4Gb # Disk image size.
memory = 128Mb # Memory size
swap = 128Mb # Swap size
fs = ext3 # use the EXT3 filesystem for the disk image.
dist = etch # Default distribution to install.
image = sparse # Specify sparse vs. full disk images.
Create a home for all the coming virtual Xen guests:
mkdir /home/xen
mkdir /home/xen/domains
And then ready to create a virtual machine – guest, simply by:
xen-create-image -hostname=mailserver -ip=10.0.0.21 -netmask=255.255.255.0 -gateway=10.0.0.1 -passwd
Afterwards I was able to fire up the newly created virtual machine with:
xm create mailserver.cfg
If an error like this shows up
Error: Device 0 (vif) could not be connected. Backend device not found.
You should check your that you have enabled the network bridge, “(network-script network-bridge)”, in /etc/xen/xend-config.sxp and restarted the xen deamon by /etc/init.d/xend restart
When up and running either “xm list” or “xentop” can be used to get an overview of what instance are currently running
debian5:# sudo xm list
Name ID Mem(MiB) VCPUs State Time(s)
Domain-0 0 874 1 r----- 657.9
mailserver 3 128 1 -b---- 8.0
Based on my experiences so far with virtualization and deploying virtualization in a enterprise setup, I really think that Xen is a very strong asset for Linux and Linux based distributions to show the world what they are up to. Virtualization is really a technique for enterprise server and data center managers to make a more robust and simplified setup, and I think that virtualization could play a significant role within the server market the coming years.