[Linux-cluster] Xen virtual machine fencing

[Lon Hohberger]

Hi,

I committed an updated agent for fencing Xen virtual machines to CVS.
It allows fencing of any virtual machine from any other host in the
cluster, and handles the case where the VM no longer exists.  Note that
there is no 'on' function mostly due to the fact that it would require a
lot of configuration knowledge about the VM which is currently not
available.

The README is not 100% complete, and neither are any of the features
mentioned in TODO. ;)

Basically, here's how to get it running:

  - build (requires nss, openais, cman, & nspr development stuff)
  - install openais + cman
  - generate a key file (e.g. dd if=/dev/urandom
    of=/etc/cluster/fence_xvm.key bs=4096 count=1)
  - scp /etc/cluster/fence_xvm.key to all dom0 cluster nodes.
  - start cman
  - start fence_xvmd with whatever options you like on all members of
    the dom0 cluster (must be started with same options cluster-wide
  - start domU nodes
  - scp /etc/cluster/fence_xvm.key to all domU machines.
  - install fence_xvm on domU nodes
  - fence_xvm -H <name of domU>  || fence_xvm -u -H <uuid>
    (boom)

If anyone wants to take up the ball on anything in the TODO, let me
know.  (If you want to implement the SSL part, you need to use the
nss/nspr libraries, and NOT openssl, due to licensing and other
reasons).

-- Lon