[ovirt-users] Fake power management?

[mots]

Hello Eli,

If I replace "/usr/bin/vdsm-tool service-restart vdsmd" with "echo b > /proc/sysrc-trigger", will the Engine consider the node to be fenced and restart the VMs that were running on it on another node? I don't see a mechanism to inform the engine that this was a "hard" fencing operation and that it's save to restart the guests.
 
Regards,

mots
 
-----Ursprüngliche Nachricht-----
> Von:Eli Mesika <emesika at redhat.com <mailto:emesika at redhat.com> >
> Gesendet: Son 16 November 2014 03:00
> An: Patrick Lottenbach <pl at a-bot.ch <mailto:pl at a-bot.ch> >
> CC: users at ovirt.org <mailto:users at ovirt.org> 
> Betreff: Re: [ovirt-users] Fake power management?
> 
> 
> 
> ----- Original Message -----
> > From: "Sandro Bonazzola" <sbonazzo at redhat.com <mailto:sbonazzo at redhat.com> >
> > To: "mots" <mots at nepu.moe <mailto:mots at nepu.moe> >, users at ovirt.org <mailto: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 <http://lists.ovirt.org/mailman/listinfo/users> 
> > > 
> > 
> > 
> > --
> > Sandro Bonazzola
> > Better technology. Faster innovation. Powered by community collaboration.
> > See how it works at redhat.com
> > _______________________________________________
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> > Users at ovirt.org <mailto:Users at ovirt.org> 
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> > 
> 

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