[ovirt-users] Power Management - but no LO?

[Eli Mesika]

----- Original Message -----
> From: "Daniel Helgenberger" <daniel.helgenberger at m-box.de>
> To: "Eli Mesika" <emesika at redhat.com>
> Cc: users at ovirt.org
> Sent: Wednesday, November 19, 2014 7:26:56 PM
> Subject: Re: [ovirt-users] Power Management - but no LO?
> 
> Hello Eli,
> 
> thanks for getting back to me. Sadly the matter does not seem quite
> clear for me right now; at least I have to read deeper into fence agents.
> 
> On 19.11.2014 10:26, Eli Mesika wrote:
> >
> >
> > ----- Original Message -----
> >> From: "Daniel Helgenberger" <daniel.helgenberger at m-box.de>
> >> To: users at ovirt.org
> >> Sent: Tuesday, November 18, 2014 5:46:07 PM
> >> Subject: [ovirt-users] Power Management - but no LO?
> >>
> >> Hello,
> >>
> >> I am toying an idea involving using oVirt's PM capabilities (esp. the
> >> cluster power_saving policy) in conjuration with some consumer grate
> >> hosts for raw compute applications.
> >>
> >> Now, these hosts do not have any lights out or BMC capabilities.
> >> However, they could be started with WOL packets.
> >>
> >> Is there a way how this can be done in oVirt? Shutting down hosts with
> >> ssh and starting them with WOL?
> >
> > Yes, but you will have to write your own custom fencing script for that and
> > configure it as explain in
> > http://www.ovirt.org/Custom_Fencing (look in the oVirt 3.5 section)
> Is there any more documentation available? I found some older docs [1],
> are they still valid?
> I struggle with how the mapping is done from parameters in the PM tab to
> functions in my fence agent, how it is passed to it and how it gets
> called in the end.

Please have a look on this lecture I had gave on hangouts : https://www.youtube.com/watch?v=IuRPGU7nF1E
I believe that it will make you understand the flow and the configuration 

> As I understood so far, oVirt needs to proxy PM/fencing operations and
> is using one host of the cluster for fencing; 

right , but if not found in cluster then dc is searched ...

>and PM the appropriate
> device. Also, I can use engine-config register the fence agent as well
> as to map some generic fields.

Yes, this is the point were you customizing the new agent 
this is basically a 2 step task

1) server side, you will have to add your fencing scripts and verify that it installs correctly in /usr/sbin/
   it must be called fence_<agent_name>
   it must obey to fence-agents package script parameters defined in
   https://fedorahosted.org/cluster/wiki/FenceArguments

2) engine side : use engine-config to configure your new agent 

> 
> >
> > If you need any details, please ask but mainly you should look on the
> > scripts in the fence-agents package (/usr/sbin/fence_*) and write
> > something that supports the common flags used by those scripts
> Some basic design concepts I thought of so far:
> I assume the virsh fence agent could work for me. It ssh's to the host.
> I would call shutdown in this case I think?
> Further, while compiling the appropriate WOL packet seems trivial in
> python, I need to map an NIC MAC address witch I could get from a
> parameter in the PM setup. But in this case, any host could be used
> execute the script; preferring the engine in this case? Or is this a bad
> approach for some reason? (Assuming the NIC is part of ovirt management
> net).
> 
> I think I can manage to do this once I have figured out the basic stuff.
> Strangely, though I found posts by people who also tried to attempt a
> WOL fence agent this as not been accomplished it seems. Can you think of
> a reason? (I can think of shutdown, witch needs ssh to be done).

There is s RFE on adding WOL support, not target version for that yet ....

> 
> Thanks for any help on the issue.
> 
> [1] http://www.ovirt.org/Features/HostPMProxyPreferences
> >
> >
> >>
> >> Thanks!
> >>
> >> --
> >> Daniel Helgenberger
> >> m box bewegtbild GmbH
> >>
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> >> F: +49/30/2408781-10
> >>
> >> ACKERSTR. 19
> >> D-10115 BERLIN
> >>
> >>
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> >> http://lists.ovirt.org/mailman/listinfo/users
> >>
> >
> 
> --
> Daniel Helgenberger
> m box bewegtbild GmbH
> 
> P: +49/30/2408781-22
> F: +49/30/2408781-10
> 
> ACKERSTR. 19
> D-10115 BERLIN
> 
> 
> www.m-box.de  www.monkeymen.tv
> 
> Geschäftsführer: Martin Retschitzegger / Michaela Göllner
> Handeslregister: Amtsgericht Charlottenburg / HRB 112767
>