Xen-test-debian

Xen HOWTOS for Debian

Installing Xen basic packages in Debian

Udpate the APT repository

 apt-get update

Install the Xen hypervisor. Note that the version may have changed: search for the current one using 'apt-get search xen-hypervisor'. Default hypervisor supports up to 4GB of physical RAM, the -pae version up to 64GB of physical RAM (we are considering the former here).

 apt-get install xen-hypervisor-3.0.3-1-i386

Install the Xen kernel:

 apt-get install linux-image-xen-686

Install Xen tools:

 apt-get install xen-tools

Install the libc6-xen (I'm not sure what it's for or even if this installation could be omitted):

 apt-get install libc6-xen

All packages in the same command:

 apt-get install xen-hypervisor-3.0.3-1-i386 linux-image-xen-686 xen-tools libc6-xen

Create the first virtual machine

Create a working directory (e.g., /root/xen.test)

 mkdir /root/xen-test

Edit the /etc/xen-tools/xen-tools.conf file. The gateway= value used here could be not appropiated for you.

 dir    = /root/xen-test
 size   = 1Gb
 memory = 32Mb
 swap   = 128Mb
 fs     = ext3
 dist   = sarge
 image  = sparse
 gateway = 192.168.247.2
 netmask = 255.255.255.0
 passwd  = 1
 kernel  = /boot/vmlinuz-2.6.18-3-xen-686
 initrd  = /boot/initrd.img-2.6.18-3-xen-686
 mirror  = http://ftp.us.debian.org/debian/

Create the first virtual machine (it will take a LONG time). Use a proper IP for you.

 xen-create-image --hostname=test --ip=192.168.247.140 --passwd --debootstrap

This creates the necesary files under /root/xen-test. However, the key file descring the virtual machine is /etc/xen/test.cfg. What xen-create-image has put in test.cfg is the following:

 kernel  = '/boot/vmlinuz-2.6.18-3-xen-686'
 ramdisk = '/boot/initrd.img-2.6.18-3-xen-686'
 memory  = '32'
 root    = '/dev/sda1 ro'
 disk    = [ 'file:/root/xen-test/domains/test/disk.img,sda1,w', 'file:/root/xen-test/domains/test/swap.img,sda2,w' ]
 name    = 'test'
 vif     = [ 'ip=192.168.247.140' ]
 on_poweroff = 'destroy'
 on_reboot   = 'restart'
 on_crash    = 'restart'

In order to boot the machine (note that you don't have to specify the complete pathname of test.cfg, it seems that xm looks in /etc/xen by default). It also can take a while to boot the virtual machine.

 xm create test.cfg -c

Troubleshooting

• If you have problems related with memory when booting virtual machines, you may find useful the dom0_mem kernel switch. Edit your GRUP configuration so your kernel line looks like this:

 kernel /boot/xen-3.0.3-1-i386.gz dom0_mem=512M

changing 512 for the desired memory in your case, of course. NOte that if you use a dom0_mem value to close to your actual physical RAM memory you will get a panic error when booting the host: as a hint dom0_mem<= phy_mem-32M (assuming the Xen hypervirso consumes less than 32MB).

Uselful references

http://www.debian-administration.org/articles/396