primary vm:
kvm -boot c -m 4096 -smp 2 -qmp stdio -vnc :7 -name primary -enable-kvm -cpu qemu64,+kvmclock -device piix3-usb-uhci \
 -drive if=virtio,id=colo-disk0,driver=quorum,read-pattern=fifo,vote-threshold=1,children.0.file.filename=/vms/images/win7.qcow2,children.0.driver=qcow2 \
 -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup.new,downscript=/etc/qemu-ifdown.new  \
 -device e1000,id=e0,netdev=hn0,mac=52:a4:00:12:78:66  \
 -chardev socket,id=mirror0,host=172.16.204.13,port=9003,server,nowait \
 -chardev socket,id=compare1,host=172.16.204.13,port=9004,server,nowait  \
 -chardev socket,id=compare0,host=172.16.204.13,port=9001,server,nowait  \
 -chardev socket,id=compare0-0,host=172.16.204.13,port=9001 \
 -chardev socket,id=compare_out,host=172.16.204.13,port=9005,server,nowait \
 -chardev socket,id=compare_out0,host=172.16.204.13,port=9005  \
 -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 \
 -object filter-redirector,netdev=hn0,id=redire0,queue=rx,indev=compare_out  \
 -object filter-redirector,netdev=hn0,id=redire1,queue=rx,outdev=compare0  \
 -object colo-compare,id=comp0,primary_in=compare0-0,secondary_in=compare1,outdev=compare_out0

secondary vm: 
kvm -boot c -m 4096 -smp 2 -qmp stdio -vnc :7 -name secondary -enable-kvm -cpu qemu64,+kvmclock -device piix3-usb-uhci \
  -drive if=none,id=colo-disk0,file.filename=/vms/images/win7.qcow2,driver=qcow2,node-name=node0 \
  -drive if=virtio,id=active-disk0,driver=replication,mode=secondary,file.driver=qcow2,top-id=active-disk0,file.file.filename=/run/shm/active_disk.img,file.backing.driver=qcow2,file.backing.file.filename=/run/shm/hidden_disk.img,file.backing.backing=colo-disk0 \
  -netdev tap,id=hn0,vhost=off,script=/etc/qemu-ifup.new,downscript=/etc/qemu-ifdown.new \
  -device e1000,netdev=hn0,mac=52:a4:00:12:78:66 \
  -chardev socket,id=red0,host=172.16.204.13,port=9003 \
  -chardev socket,id=red1,host=172.16.204.13,port=9004 \
  -object filter-redirector,id=f1,netdev=hn0,queue=tx,indev=red0 \
  -object filter-redirector,id=f2,netdev=hn0,queue=rx,outdev=red1 \
  -object filter-rewriter,id=rew0,netdev=hn0,queue=all -incoming tcp:0:8888
  
on secondary vm: 
{'execute':'qmp_capabilities'}
{ 'execute': 'nbd-server-start',
  'arguments': {'addr': {'type': 'inet', 'data': {'host': '172.16.204.21', 'port': '8889'} } }
}
{'execute': 'nbd-server-add', 'arguments': {'device': 'colo-disk0', 'writable': true } }

on primary vm:
{'execute':'qmp_capabilities'}
{ 'execute': 'human-monitor-command',
  'arguments': {'command-line': 'drive_add -n buddy driver=replication,mode=primary,file.driver=nbd,file.host=172.16.204.21,file.port=8889,file.export=colo-disk0,node-name=node0'}}
{ 'execute':'x-blockdev-change', 'arguments':{'parent': 'colo-disk0', 'node': 'node0' } }
{ 'execute': 'migrate-set-capabilities',
      'arguments': {'capabilities': [ {'capability': 'x-colo', 'state': true } ] } }
{ 'execute': 'xen-set-replication', 'arguments': {'enable': true, 'primary': true } }
{ 'execute': 'migrate', 'arguments': {'uri': 'tcp:172.16.204.21:8888' } }