[geeks] the virtualization project

[Patrick Finnegan]

On Saturday, September 17, 2011, Shannon wrote:
> On Sep 17, 2011, at 10:09 , Patrick Finnegan wrote:
> > On Friday, September 16, 2011, Shannon wrote:
> >> On Sep 9, 2011, at 11:24 , Bill Bradford wrote:
> >>> On Fri, Sep 09, 2011 at 12:17:01AM -0400, Shannon wrote:
> >>> 
> >>> ohno.mrbill.net is a Debian 6 quad-core (AMD Athlon II 640)
> >>> system with 16 of RAM, with ohno being the "native" host system.
> >>>  I'm also running three different VMs under Qemu/KVM; two Debian
> >>> 6 and one FreeBSD, paravirtualized (virtio) drivers being used
> >>> when possible.  It's been "in production" for 9-10 months now
> >>> and works *great*.
> >> 
> >> I spent last nite and this morning installing Debian squeeze.
> >> 
> >> I could not try KVM because the machine has no HVM support, so I
> >> tested Xen.
> >> 
> >> The GUI tools for LVM, Xen, and KVM all seem broken, so I gave up
> >> playing with them. I was just curious about them. Using the
> >> command line tools was just faster and easier.
> > 
> > I didn't realize there were gui tools. Why put a gui on your Dom0
> > box?
> > 
> > :)
> 
> "I was just curious about them." :)
> 
> The default install for Debian includes all kinds of stuff, and I
> didn't see a "small install" option so I just hit default.

You want to set the install mode to "expert", and select nothing at the 
"select and install packages" part of the installer.  You get a really 
small system that way (a few hundred MB).
 
> Also even some command line Xen stuff pulled in tons of GUI code...
> :(

Not if you're doing it right.  Look at what you get back from an "apt-
cache search ^xen".  You'll want to apt-get install xen-hypervisor-blah, 
xen-utils-blah, and xen-tools, along with a xen-enabled kernel image 
(named linux-kernel-2.6.blah-xen).
 
> >> One thing I can't make work is networking for the guest operating
> >> systems. They cannot send or receive packets.
> > 
> > Try this.
> > 
> > apt-get remove network-manager
> 
> I already did that and there was no difference.
> 
> > Set up eth0 in /etc/network/interfaces like normal. It should look
> > sorta like this:
> > 
> > auto eth0
> > interface eth0 inet static
> > 
> > 	address 192.168.0.2
> > 	netmask 255.255.255.0
> > 	gateway 192.168.0.1
> 
> I normally use DHCP with MAC addresses, but I made a static entry:
> 
> auto eth0
> iface eth0 inet static
> 	address 192.168.1.30
> 	netmask 255.255.255.0
> 	gateway 192.168.1.1
> 
> When I do this, then brctl says this:
> 
> bridge name	bridge id	STP		interfaces
> eth0		8000.blah blah	NO		peth0
> 
> I don't get that... its listing eth0 as a bridge?

Yep. Once you install Xen, it renames your physical interface to peth0, 
and creates a bridge to use for itself, named eth0.  In doing this is 
where the default gateway goes away (which you noticed in another 
message).
 
> I put the following in /etc/network/interfaces (added):
> 
> iface br0 inet static
> 	bridge_ports eth0
> 	bridge_stp on
> 	bridge_maxwait 0
> 
> Then I get log messages saying "device eth0 is a bridge itself,
> cannot slave a bridge to a bridge".

Right.
 
> I'm confuzzled. When I last used Linux eth0 was the base ethernet
> device, not a bridge, so none of this makes sense right now. This
> stuff does not work the way the documentation says.

eth0 got renamed to peth0 by xen.  When you're using xen to bridge the 
network, you want to ignore the physical device for *everything* (except 
maybe ethtool, to see if there's link), and use eth0 for everything.

> Now "ifdown eth0" results in "interface eth0 not configured", but its
> up.
> 
> ifconfig eth0 down
> ifconfig peth0 down
> ifup eth0
> 
> That sequenced brings eth0 back up with no br0 in the configuration
> since I can't create it anyway.

Yes, since eth0 is the bridge made from peth0.  IIRC, peth0 will have to 
be up for the bridge device (eth0) to work.

> Still no work.
> 
> Will keep playing.
> 
> > Now, you want something like this in your /etc/xen/xend-config.sxp:
> > (network-script 'network-bridge bridge=br1')
> > (vif-script vif-bridge)
> > 
> > And your blah.cfg for your domain should have something like this
> > in it: vif = ['bridge=br1']
> 
> Yea I have all that, tried with and without the bridge statement.
> 


-- 
Patrick Finnegan