[ovirt-users] Fake power management?

[Eli Mesika]

----- Original Message -----
> From: "Sandro Bonazzola" <sbonazzo at redhat.com>
> To: "mots" <mots at nepu.moe>, users at ovirt.org
> Sent: Friday, November 14, 2014 5:15:25 PM
> Subject: Re: [ovirt-users] Fake power management?
> 
> Il 14/11/2014 15:54, mots ha scritto:
> > Hello,
> > 
> > I'm building a small demonstration system for our sales team to take to a
> > customer so that they can show them our solutions.
> > Hardware: Two Intel NUC's, a 4 port switch and a laptop.
> > Engine: Runs as a VM on one of the NUCs, which one it runs on is determined
> > by pacemaker.
> > Storage: Also managed by pacemaker, it's drbd backed and accessed with
> > iscsi.
> > oVirt version: 3.5
> > OS: CentOS 6.6
> 
> Just for curiosity, any reason for using pacemaker instead on oVirt Hosted
> Engine solution?
> 
> > 
> > The idea is to have our sales representative (or the potential customer
> > himself) randomly pull the plug on one of the NUCs to show that the system
> > stays operational when part of the hardware fails.
> > My problem is that I don't have any way to implement power management, so
> > the Engine can't fence nodes and won't restart guests that were running on
> > the node which lost power. In pacemaker I can just configure fencing over
> > SSH or even disable the requirement to do so completely. Is there
> > something
> > similar for oVirt, so that the Engine will consider a node which it can't
> > connect to to be powered down?

Well, we are thinking of adding such ability (Fake power management) mainly for testing purpose...
Meanwhile, I think I have a work-around that may help you.

When we have a connectivity issue with a node, we first try (after a grace period) to restart its VDSM via SSH 
this is always done before the hard-fencing (restart via the PM card) and can be done no matter if the host has PM configured or not.
So basically when a connectivity issue is found, you can custom the SSH command that restarts VDSM to do whatever you want, even a script or a power-down command 

look at the result of 

> psql -U engine -c "select * from vdc_options  where option_name ilike  'SshSoftFencingCommand'" engine

 option_id |      option_name      |               option_value               | version
-----------+-----------------------+------------------------------------------+---------
       558 | SshSoftFencingCommand | service vdsmd restart                    | 3.0
       559 | SshSoftFencingCommand | service vdsmd restart                    | 3.1
       560 | SshSoftFencingCommand | service vdsmd restart                    | 3.2
       561 | SshSoftFencingCommand | /usr/bin/vdsm-tool service-restart vdsmd | 3.3
       562 | SshSoftFencingCommand | /usr/bin/vdsm-tool service-restart vdsmd | 3.4
       563 | SshSoftFencingCommand | /usr/bin/vdsm-tool service-restart vdsmd | 3.5


Please note:

1) change only the value that match your cluster version
2) restart engine so change can take place 
3) restore to default value again after you are done 

Does this may be useful for you ?



> > 
> > Regards,
> > 
> > mots
> > 
> > 
> > _______________________________________________
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> > http://lists.ovirt.org/mailman/listinfo/users
> > 
> 
> 
> --
> Sandro Bonazzola
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