Creating a Xen image

A friend of mine recently lost access to his server and so I figured I'd try and create him a virtual machine on one of my boxes while he was getting his back online.

"No worries", think I, "I'll just install something like KVM and it'll all be good". Unfortunatly I found out that the CPUs in my server (dual core P4 Xeon 3Ghz in a Dell 2850) don't support the Intel-VT instruction set neded to run KVM. "Well, ok, I'll just some something like 'apt-get install ubuntu-xen-server' and all will be good"...

 

Unfortunatly it turned out to be more complex than that -- here is what I did to get it working, so next time I don't waste 3 hours poking at this.

 

The Intrepid xen packages install 'xen-3.3.gz' in /boot, but there are there is no kernel or modules file. Turns out the repository doesn't have those, so you need to do:

Kernel: http://packages.debian.org/lenny/i386/linux-image-2.6.26-2-xen-686/download

Modules: http://packages.debian.org/lenny/i386/linux-modules-2.6.26-2-xen-686/download


Then install using

sudo dpkg -i linux-image-2.6.26-2-xen-686_2.6.26-15lenny2_i386.deb linux-modules-2.6.26-2-xen-686_2.6.26-15lenny2_i386.deb 

 

After that I made the virtual machine and started it - "Hmmm, this is too easy...", and sure enough, it was...

 

Connecting to the virtual console only gave me:

starting system log daemon: syslogd.
Starting kernel log daemon: klogd.
* Not starting internet superserver: no services enabled.
Starting OpenBSD Secure Shell server: sshd[    8.032223] NET: Registered protocol family 10
[    8.032777] lo: Disabled Privacy Extensions
.
Starting periodic command scheduler: crond.

 

and then nothing -- I figured I'd try and loging over ssh, but the install process hadn't prompted me for a root password. I mounted the dis image and added a user, then tried logging in over ssh. Still no luch, I got:

 

After much prodding I got everyting working correctly, here is how:

 

The general config is in /etc/xen-tools/xen-tools.conf

To create the image do:

 root@machine:/etc/xen-tools# sudo xen-create-image --hostname=xen1.example.com --ip xx.xx.xx.xx --ide --force --passwd --role udev
General Information
--------------------
Hostname  : xen1.example.com
Distribution  : lenny
Partitions  : swap 128Mb (swap)
/ 4Gb (ext3)
Image type  : sparse
Memory size  : 128Mb
Kernel path  : /boot/vmlinuz-2.6.26-2-xen-amd64
Initrd path  : /boot/initrd.img-2.6.26-2-xen-amd64
Networking Information
----------------------
IP Address 1  : xx.xx.xx.xx [MAC: 00:16:3E:xx:xx:xx]
Netmask  : xx.xx.xx.xx
Gateway  : xx.xx.xx.xx
Creating partition image: /home/xen/domains/xen1.example.com/swap.img
Done
Creating swap on /home/xen/domains/xen1.example.com/swap.img
Don
Creating partition image: /home/xen/domains/xen1.example.com/disk.img
Done
Creating ext3 filesystem on /home/xen/domains/xen1.example.com/disk.img
Done
Installation method: debootstrap
...

To start the image, do:

 root@machine:/etc/xen-tools# sudo xm create /etc/xen/xen1.example.com.cfg

To connect to the console, run

xm console xen1.example.com

. To disconnect the console, its ^-[ The config file for xen-tools is:

/etc/xen-tools/xen-tools.conf
dir = /home/xen
...
#
##
# Disk and Sizing options.
##
#
size = 4Gb # Disk image size.
memory = 128Mb # Memory size
swap = 128Mb # Swap size
# noswap = 1 # Don't use swap at all for the new system.
fs = ext3 # use the EXT3 filesystem for the disk image.
dist = lenny # Default distribution to install.
image = sparse # Specify sparse vs. full disk images.
...
# Uncomment and adjust these network settings if you wish to give your
# new instances static IP addresses.
#
netmask = xx.xx.xx.xx
gateway = xx.xx.xx.xx
...
#
# Uncomment the following line if you wish to interactively setup
# a new root password for images.
#
passwd = 1
...
#
# If you're using a newer version of the Xen guest kernel you will
# need to make sure that you use 'xvc0' for the guest serial device,
# and 'xvdX' instead of 'sdX' for serial devices.
#
# You may specify the things to use here:
serial_device = hvc0

 

Additional information