Enable graceful shutdown for Windows guests on XEN hosts

[fred]

Background

Currently, our Windows Server OS cannot be shutdown or rebooted (gracefully) from the XEN host. But this is necessary when the XEN host has to shutdown all VMs automatically, e.g. in case of a power outage when the UPS battery runs out or for in general for a reboot of the XEN host.

What to change

There exists a set of open source XEN PV drivers for Windows that (besides a noticeable performance increase on the Windows guest) allows for signalling a graceful shutdown / reboot command from the XEN host.
They can be downloaded from here:
​http://wiki.univention.de/index.php?title=Installing-signed-GPLPV-drivers
These drivers should be installed on VMs server4 and server2.

[fred]

The XEN PV drivers for Windows have been installed on server4.

[fred]

The XEN PV drivers for Windows have been installed on server2.

Now a real-life test of the graceful shutdown of the Windows VMs via the power management tools on the XEN host (xen1) is still needed.

[fred]

Shutdown procedure tests have been performed during a maintenance window an showed, that the /etc/init.d/xendomains init script provided by the ubuntu 14.04 XEN packages has a bug (see ​https://bugs.launchpad.net/ubuntu/+source/xen/+bug/1178625) that prevents the guest VMs to be properly shutdown.

So after a certain timeout is hit, the VMs are switched off without further notice to the guest OS, resulting in complaints by the guest OS about an unclean shutdown and potentially in data-loss.

After applying a patch provided in the bug report mentioned above, the xendomains script is able to properly notify the guest OS to trigger a clean shutdown.