Open Stack

On Tue, Dec 02, 2014 at 08:48:52PM -0500, Steve Gordon wrote:
> ----- Original Message -----
> > From: "Stefano Maffulli" <stefano at openstack.org>
> > To: "Daniel P. Berrange" <berrange at redhat.com>, Enterprise-wg at lists.openstack.org
> > 
> > hi Daniel,
> > 
> > during today's meeting for the Win The Enterprise working group we
> > noticed libvirtWatchdog. The wiki page
> > https://wiki.openstack.org/wiki/LibvirtWatchdog is authored by you
> > originally so I'm reaching out to learn more about the status of this
> > feature.
> >
> > In the WTE team, one of the priorities is to understand the status of
> > features that allow non-ephemeral (persistent) workloads on OpenStack
> > (aka the "pet" use case). libvirtWatchdog was mentioned during a session
> > in Paris, saying that it currently supports KVM and Linux guests only.
> > 
> > What are the plans for its future (can/should it be extended to other
> > guests/hypervisors)? Who's maintaining it at the moment? Is there any
> > other documentation besides the wiki page?
> 
> I'll take a crack at it and then Dan can tell me how wrong I am since it's probably my fault it was in the etherpad ;). The watchdog feature in OpenStack is exposing capabilities in the underlying Libvirt [1] and Qemu [2][3] layers which allow you to attach an i6300esb watchdog device to the guest and assign a lifecycle action to take if it is triggered. Fundamentally there's nothing preventing other hypervisor projects from implementing this, I'm not sure which ones if any actually have however (and when I cover the second part of your question below it might become clear why).
> 
> As to why it only works with Linux guests (or more accurately why it doesn't work for Windows - I wouldn't be surprised if the BSD family or other OSes do support it to some degree but I've never checked) I believe it was originally intended to but there were a few issues uncovered during the chase, in particular:
> 
> 1) The default Window's driver for the device only displays the PCI information for it (it doesn't actually do anything with the device).
> 
> 2) The Intel driver for this device on Windows only ever worked with 32-bit editions of Windows.
> 
> 3) The Intel driver for this device on Windows always assumes it's in a specific PCI slot.
> 
> 4) There's no framework within Windows for triggering a watchdog device and we weren't able to determine if there were any Windows applications capable of  triggering one either.
> 
> Basically while you can attach the device to a Windows guest for it to actually be used it would require someone to write a proper driver for the device that works on Windows and there would need to be applications that know how to actually make use of it. In the Linux case I believe there is wider support for it and it can be triggered by common panics and lockups (Rich's blog [3] gives some more examples).
> 
> For the gorier details see: https://bugzilla.redhat.com/show_bug.cgi?id=610063.

Yep, that's pretty much it.

Also note there's a missing feature in Nova in that we have no mechanism
to notify the end user when a watchdog fires on their VMs. Libvirt has
this notification ability but we've nowhere to send this info in OpenStack.
We need some kind of formal alerting system to get a message back to the
end user (or to an ochestration tool like Heat),  so they can take action
when it fires.

Regards,
Daniel
-- 
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