KVM: VM creation

Create Torque reservation

Establish a SSH connection to a compute node using X-forwarding:

ssh -X arc.csc.ncsu.edu
qsub -I -X ...

Create VM

• /usr/local/bin/virt-install-wrapper.sh is a wrapper for virt-install which takes all the commandline arguments you would normally pass to virt-install.
• /usr/local/bin/virt-install-wrapper.sh must be invoked with sudo.
• Disk images must be stored in /tmp, not /home. Shut down your VM and copy the disk image to login-0-0:/tmp/ before termination of your reservation. Again, please do NOT use /home to store Gigabyte sized images!!!
• Interactive installs using --prompt are not supported.
• Select a MAC address following the MAC guidelines.
• For example, to create a CentOS VM named testvm, use the following command:

  sudo /usr/local/bin/virt-install-wrapper.sh \
  --name testvm \
  --ram 500 \
  --file-size 5 \
  --nographics \
  -l ftp://ftp.linux.ncsu.edu/pub/centos/5.5/os/x86_64 \
  --file /tmp/testvm.img \
  --extra-args='console=tty0 console=ttyS0,115200n8' \
  --accelerate \
  --vcpus=2 \
  --network bridge:br0 \
  --mac=54:52:00:00:xx:yy

  The same command on a single line:

  sudo /usr/local/bin/virt-install-wrapper.sh --name testvm --ram 500 --file-size 5 --nographics -l ftp://ftp.linux.ncsu.edu/pub/centos/5/os/x86_64 --file /tmp/testvm.img --extra-args='console=tty0 console=ttyS0,115200n8' --accelerate --vcpus=2 --network bridge:br0 --mac=54:52:00:00:xx:yy

  In this case we assume a network install. However, an ISO can be downloaded and used if needed.
• NOTE: br0 must be specified as the network bridge.
• NOTE: CentOS / RHEL guests require the 'console=...' kernel parameter so that the text-based installation works.

Fix MAC and enable VNC

• Upon completion of the text-based installation, you will be greeted with a login prompt. Press Ctrl-] to exit the console connection.
• NOTE: All virsh commands must always include the -c qemu:///system parameter.

  virsh -c qemu:///system ...

• Dump your VM's XML file so it can be edited.

  virsh -c qemu:///system dumpxml testvm > testvm.xml

• Edit testvm.xml by adding this line to enable VNC, in the <devices> section:

  <graphics type='vnc' port='5900'/>

• Destroy your VM and remove it from virsh, so you can reload the edited XML.

  virsh -c qemu:///system destroy testvm
  virsh -c qemu:///system undefine testvm

• Add your edited XML to virsh and start the VM again.

  virsh -c qemu:///system define testvm.xml
  virsh -c qemu:///system start testvm

Complete installation with VNC

• Use virsh to discover the VNC display for your VM:

  virsh -c qemu:///system vncdisplay testvm

• Use VNC to complete the post-install routine for your OS (assuming you've correctly configured X-forwarding):

  vncviewer 127.0.0.1:<display number>

• NOTE: virsh console will not work due to permissions issues. The installation must be completed using VNC.
• Once finished, open a terminal using VNC and determine your IP address:

  /sbin/ifconfig eth0

• SSH should work to/from the VM / physical host.

Use multiple guests

• Copy you your image file to create an identical guest:

  cp /tmp/testvm.img /tmp/testvm2.img

• Dump your VM's XML file so it can be edited.

  virsh -c qemu:///system dumpxml testvm > testvm2.xml

• Edit testvm2.xml file to change the MAC (to a different one than the one in testm.xml):

  <mac address='54:52:00:00:xx:aa'/>

  See MAC guidelines.
• Add your testvm2.xml to virsh and start the VM.

  virsh -c qemu:///system define testvm2.xml
  virsh -c qemu:///system start testvm2