Running in KVM

Installing CernVM on KVM

CernVM images for KVM (Kernel-based Virtual Machine) are intended to be used by experienced users, or by system administrators (e.g. in unatended environments like Grid worker nodes).For creating and controlling virtual machines with KVM we recommend using libvirt (in particular 'virsh' command line utility) and virt-manager graphical tool.

Prerequisies

• Make sure that your host supports kvm (the output of the command should not be empty)
  

   egrep '(vmx|svm)' --color=always /proc/cpuinfo

• Make sure that the necessary packages are installed
  

  # rpm -qa | egrep 'kvm|bridge-utils|tunctl|virt-manager|libvirt'
  kmod-kvm-83-164.el5_5.30.x86_64
  bridge-utils-1.1-2.x86_64
  kvm-83-164.el5_5.30.x86_64
  kvm-tools-83-164.el5_5.30.x86_64
  virt-manager-0.6.1-12.el5.x86_64
  kvm-qemu-img-83-164.el5_5.30.x86_64
  etherboot-zroms-kvm-5.4.4-13.el5.x86_64
  libvirt-0.6.3-33.el5_5.3.x86_64
  #
  		

• Make sure that the kvm kernel module is loaded (if not insert it with 'modprobe kvm-intel' or 'modprobe kvm-amd')
  

   # lsmod|grep kvm

  If not insert the module with one of the following commands.
  For Intel machines

  # modprobe kvm-intel

  For AMD machines

  # modprobe kvm-amd

• Make sure that the permissions of /dev/kvm file are set to 0666. The file should be owned by 'root', and the group ownership should be set to 'kvm'
  

  # ls -al  /dev/kvm
  crw-rw---- 1 root kvm 10, 232 Oct 19 14:49 /dev/kvm

• Make sure that KVM network is properly set up for using NAT
  

  # virsh net-dumpxml default
  <network>
    <name>default</name>
    <uuid>a6ae5d2a-8ab5-45a9-94b2-62c29eb9e4f4< /uuid>
    <forward mode='nat'/>
    <bridge name='virbr0' stp='on' forwardDelay='0' />
    <ip address='192.168.122.1' netmask='255.255.255.0'>
      <dhcp>
        <range start='192.168.122.2' end='192.168.122.254' />
      </dhcp>
    </ip>
  </network>
  #	
  		

Creating a Virtual Machine

If you plan to run on an unattended environment like (e.g. a worker node) start form either 'Batch Node' or 'Head node' image, otherwise use the 'Basic' image. Download CernVM image from CernVM Downloads page and unzip it.
Create a virtual machine definition file for 'virsh' (libvirt guest domain management interface), which should contain the following:

• Virtual machine name
• Memory size (in MB)
• Type of architecture ('x86_64' for 64 bit images and 'i686' for 32 bit images) and boot device ('hd')
• Hard drive definition
• Network interface definition
• Graphical device definition

Example virtual machine definition file looks like this:

<domain type='kvm'>
        <name>CernVM-2.2.0-x86_64</name>
        <memory>524288</memory>
        <os>
                <type arch='x86_64'>hvm</type>
                <boot dev='hd'/>
        </os>
        <devices>
                <disk type='file' device='disk'>
                        <source file='/data/test/cernvm-2.2.0-x86_64.hdd' />
                        <target dev='hda'/>
                </disk>
                <interface type='network'>
                        <source network='default'/>
                        <model type='virtio'/>
                </interface>        

                <graphics type='vnc' listen='0.0.0.0' port='6019'/>
         </devices>
</domain>

Virtual machine is created with the following command:

# virsh create vm-definition.xml

Virtual machines can be listed, started and stopped with:

# virsh list 
 Id Name                 State
----------------------------------
 18 CernVM-2.2.0-x86_64 running

# virsh shutdown CernVM-2.2.0-x86_64
Domain CernVM-2.2.0-x86_64 is being shutdown

# virsh start CernVM-2.2.0-x86_64
Domain CernVM-2.2.0-x86_64-4 started

# 

Virtual machine console can be opened using virt-manager program.

Virtual machine configuration

Please refer to the final CernVM configuration step to configure the virtual machine for a specific experiment.