[CentOS] Virtualization platform choice

Sun Mar 27 18:23:49 UTC 2011
Nataraj <incoming-centos at rjl.com>

On 03/27/2011 07:10 AM, Steve Thompson wrote:
> On Sun, 27 Mar 2011, Nico Kadel-Garcia wrote:
>
>> How did you get the PXE working?
> I already had a PXE server for physical hosts, so I just did a 
> virt-install with the --pxe switch, and it worked first time. The MAC 
> address was pre-defined and known to the DHCP server. I installed both 
> Linux and Windows guests with PXE.
>
>> And do you have widgets for setting up the necessary bridged
>> networking?
> I edited the ifcfg-eth0 file on the host and added an ifcfg-br0, all by 
> hand, and then rebooted. I didn't have to think about it again.
>
> /etc/sysconfig/network-scripts/ifcfg-eth0:
>  	DEVICE=eth0
>  	HWADDR=xx:xx:xx:xx:xx:xx
>  	ONBOOT=yes
>  	BRIDGE=br0
>  	NM_CONTROLLED=0
>
> /etc/sysconfig/network-scripts/ifcfg-br0:
>  	DEVICE=br0
>  	TYPE=Bridge
>  	BOOTPROTO=static
>  	BROADCAST=<braddr>
>  	IPADDR=<ipaddr>
>  	NETMASK=<netmask>
>  	NETWORK=<network>
>  	ONBOOT=yes
>
> For each guest, something like this was used:
>
>      <interface type='bridge'>
>        <mac address='52:54:00:1d:58:cf'/>
>        <source bridge='br0'/>
>        <model type='virtio'/>
>      </interface>
>
> Steve
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I setup a pxe boot server based on the instructions found here. 
https://help.ubuntu.com/community/PXEInstallMultiDistro
<https://help.ubuntu.com/community/PXEInstallMultiDistro> It works fine
for both physical machines and kvm VM's.  My pxeboot server is running
under ubuntu 10.04.2 in a kvm vm.  If your pxeboot server needs to run
under Redhat/CentOS, then you'll need to locate/install the packages
mentioned on this web page, which should be pretty straight forward.

Note the pxeboot server works fine for the install CDs and DVD's for all
of the distributions that I've tried, Redhat, Fedora and Ubuntu.  To
boot live CDs I believe you need to convert the entire image into a tftp
boot image which I think can be done using the fedora live cd creator
tool (maybe it's in redhat now as well).

I make the CD/DVD image available via NFS.  On the PXE host I simply
mount the ISO image under the NFS /export directory.  Most of the
install distributions provide the tftp images for pxeboot.  On the
redhat 6 CD you'll find vmlinuz and initrd.img in the /images/pxeboot
directory.

I just recently installed kvm virtualization on several redhat 6 hosts
and one under Scientific Linux.  The latest version of virt-manager
(with recent updates installed) now supports setup of bridge devices
from the GUI.  You'll want to make sure to use virtio for performance
and to disable the tso and gso tcp offload functions present in many
ethernet cards which I do with the upstart script listed below.

I am so far quite happy with kvm and happy to be able to run my
management interface under linux instead of windows.

#disable-tcpoffload - upstart script to modify tcp offload config for virtualization
#

description "disable-tcpoffload"

start on started rc RUNLEVEL=[2345]
stop on stopped rc RUNLEVEL=[!2345]

task

console output
# env INIT_VERBOSE

script
	set +e
	for interface in eth0 eth1 eth2 eth3; do
		/sbin/ethtool -K $interface gso off
		/sbin/ethtool -K $interface tso off
	done
end script


Nataraj





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