4.1. a) and 4.2 a)

In this setup we will create four virtual machines. Two servers for redundant
data storage and two clients, each running a dom0.

Network configuration is done using static IPs:

	server1:   10.0.2.172
	server2:   10.0.2.173
	virt_serv: 10.0.2.174
	client1:   10.0.2.83
	client2:   10.0.2.84

All of the following is executed by several factors faster after installation
of kvm for qemu:

	apt-get install qemu-kvm

The tutorial assumes a 64 bit host. For a 32 bit host, change
qemu-system-x86_64 to qemu-system-i386 and change amd64 in the installer url to
i386.

The tutorial also assumes a Debian host (any release of lenny or newer should
work) and a working apt-cacher setup. To setup apt-cacher, do:

	apt-get install apt-cacher

If you dont want to use apt-cacher, you have to adapt the package sources in
the scripts.

Get the debian wheezy installer:

wget http://cdimage.debian.org/cdimage/daily-builds/daily/arch-latest/kfreebsd-amd64/iso-cd/debian-testing-kfreebsd-amd64-businesscard.iso

Install vde for a userspace switched network between all connected qemu
instances:

	apt-get install vde2

And start it (sending it to the background) together with slirp which provides
connection to the outside using slirp networking (just as qemu user mode
networking):

	vde_switch -daemon
	slirpvde -dhcp -daemon

Starting slirp with dhcp enabled is necessary for the debian-installer to
acquire an initial IP (giving all settings as isolinux arguments is tedious and
errorprone) and for the domus to get an IP.

Create two disk images for the two server machines and two for the client
machines:

	dd if=/dev/zero of=server1.img bs=1 count=1 seek=3000MiB
	dd if=/dev/zero of=server2.img bs=1 count=1 seek=3000MiB
	dd if=/dev/zero of=client1.img bs=1 count=1 seek=3000MiB
	dd if=/dev/zero of=client2.img bs=1 count=1 seek=3000MiB

Start the machines with these images, giving them all the debian installer
cdrom and connecting them to the vde network.

	qemu-system-x86_64 -m 256 -hda server1.img -net nic,macaddr=DE:AD:BE:EF:BE:9D -net vde,sock=/tmp/vde.ctl -cdrom debian-testing-amd64-businesscard.iso
	qemu-system-x86_64 -m 256 -hda server2.img -net nic,macaddr=DE:AD:BE:EF:74:E9 -net vde,sock=/tmp/vde.ctl -cdrom debian-testing-amd64-businesscard.iso
	qemu-system-x86_64 -m 256 -hda client1.img -net nic,macaddr=DE:AD:BE:EF:D4:4A -net vde,sock=/tmp/vde.ctl -cdrom debian-testing-amd64-businesscard.iso
	qemu-system-x86_64 -m 256 -hda client2.img -net nic,macaddr=DE:AD:BE:EF:78:01 -net vde,sock=/tmp/vde.ctl -cdrom debian-testing-amd64-businesscard.iso

The isolinux boot menu will pop up. Choose "Advanced options" and then select
"Automated install" and press [TAB] to edit the boot commandline. Append the
preseed url for debconf like this to the end of each of the installers
respectively:

	preseed/url=http://mister-muffin.de/debian/server1.txt
	preseed/url=http://mister-muffin.de/debian/server2.txt
	preseed/url=http://mister-muffin.de/debian/client1.txt
	preseed/url=http://mister-muffin.de/debian/client2.txt

Press enter and get yourself a coffee. After everything is finished the
machines will automatically shut down.

Now start all machines by using:

	qemu-system-x86_64 -m 256 -hda server1.img -net nic,macaddr=DE:AD:BE:EF:BE:9D -net vde,sock=/tmp/vde.ctl -nographic
	qemu-system-x86_64 -m 256 -hda server2.img -net nic,macaddr=DE:AD:BE:EF:74:E9 -net vde,sock=/tmp/vde.ctl -nographic
	qemu-system-x86_64 -m 1000 -hda client1.img -net nic,macaddr=DE:AD:BE:EF:D4:4A -net vde,sock=/tmp/vde.ctl -nographic
	qemu-system-x86_64 -m 1000 -hda client2.img -net nic,macaddr=DE:AD:BE:EF:78:01 -net vde,sock=/tmp/vde.ctl -nographic

The two clients get more ram now because they have to host domus.

A firstboot sysv-init script will initialize drbd on the meta partition for
both servers and start the synchronization by setting server1 as the primary
host.

When this is done, extract a root filesystem of your choice into
/data/export/vm01 on server1.

Creating a root filesystem to share via nfs can be done by using debootstrap
and then manually configuring it [1] or by running xen-create-image, then
editing /etc/fstab and then putting the result on server1.

xen-create-image --hostname=vm01 --dir=/root --dhcp --noswap --size=400Mb

For convenience I did the above and put a tarball with debian wheezy online. On
server1, do:

	mkdir /data/export/vm01
	wget -O - http://mister-muffin.de/debian/nfs-root-wheezy-amd64.tar | tar -x -C /data/export/vm01

	Username: root
	Password: root

After the rootfilesystem is in place you can start the domu on client1:

	xm create /etc/xen/vm01.cfg

And migrate it to client2:

	xm migrate --live vm01 client2

tadaa! :)

1/2:

drbdadm create-md res
#drbdadm up all

1:
#drbdadm -- --do-what-I-say primary all
drbdadm -- --overwrite-data-of-peer primary all
#drbdadm -- connect all
#drbdadm primary



[1] http://blog.mister-muffin.de/2011/11/21/xen-hypervisor-on-qemu-kvm-and-domu-nfs-boot-with-vde/