KVM virtual machines on RHEL

Documenting the adventure of installing KVM virtual guests on two physical hosts, running RHEL6.

Installation of Virtualization Packages
Subscribe to RHEL Server 6 x86_64 channel via the RedHat subscriptions management page. This requires an add-on subscription. There’s a command-line way to do this as well, either “rhn-register” or “subscription-manager.”

Install the virtualization tools and X Window tools for Virt-Manager:

yum groupinstall "Virtualization" ;  yum groupinstall "X Window System"

Configuration of Bridged Networking

Edit /etc/sysconfig/network-scripts/ifcfg-eth1:

Add BRIDGE, and disable NetworkManager for this device.  Remove all specific IP information, since it will go in another file.

service NetworkManager stop ; chkconfig NetworkManager off

/etc/sysconfig/network-scripts/ifcfg-eth1:

DEVICE=eth1
ONBOOT=yes
TYPE=Ethernet
NM_CONTROLLED=no
IPV6_INIT=no
BRIDGE=br0
HWADDR=XX:XX:XX:XX:XX

Create the bridge script /etc/sysconfig/network-scripts/ifcfg-br0:

DEVICE=br0
TYPE=Bridge
BOOTPROTO=static
ONBOOT=yes
NM_CONTROLLED=no
IPADDR=192.168.1.5
NETMASK=255.255.255.0
NETWORK=192.168.1.0
DELAY=0

service network restart ; service libvirtd reload
brctl show

If firewall is running, enable bridging:

iptables -I FORWARD -m physdev --physdev-is-bridged -j ACCEPT
service iptables save
service iptables restart
service libvirt reload

Create a random, static MAC address

A unique MAC address will be needed for the virt-install process.

openssl rand -hex 6 | sed 's/\(..\)/\1:/g; s/.$//'

Note that KVM MAC addresses are recommended to start with 52:54:00, but I’ve modified a MAC address manually after the install and it still worked.

How to install VM guest with virt-install

This command references the kickstart file shared via http on the local server, and points to the local rhel6 install source.

virt-install --name=testvm1 --hvm --conect qemu:///system --network=bridge:br0 --disk path=/storage/testvm1.img,size=40 \
--graphics vnc,keymap=en-us --vcpus=2 --ram=8192 --os-type=linux --os-variant=rhel6 --mac=XX:XX:XX:XX:XX:XX \
--extra-args="ks=http://192.168.1.10/kickstart/testvm1.cfg" --location=http://192.168.1.10/rhel-6.1-x86_64/

To connect to the console via command line and watch the boot process:

virsh console testvm1

To view a graphical console for the newly created virtual machine, you may use virt-manager’s console.
virt-manager allows creation of virtual machines, and it will create a random MAC address during the VM install process. You will need to add the random MAC address into your DHCP configuration in order to grab the OS install source.

Happy virtualizing.

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