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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I tend to agree with Klaus – I don't think that having a hook that bypass stonith is the right way. It is better to not use stonith at all.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I think I will try to use an iScsi target on my qdevice and set SBD to use it.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I still don't understand why qdevice can't take the place SBD with shared storage; correct me if I'm wrong, but it looks like both of them are there for the same
reason.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext"> Klaus Wenninger [mailto:kwenning@redhat.com]
<br>
<b>Sent:</b> Monday, July 24, 2017 9:01 PM<br>
<b>To:</b> Cluster Labs - All topics related to open-source clustering welcomed <users@clusterlabs.org>; Prasad, Shashank <ssprasad@vanu.com><br>
<b>Subject:</b> Re: [ClusterLabs] Two nodes cluster issue<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On 07/24/2017 07:32 PM, Prasad, Shashank wrote:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Sometimes IPMI fence devices use shared power of the node, and it cannot be avoided.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">In such scenarios the HA cluster is NOT able to handle the power failure of a node, since the power is shared with its own fence device.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">The failure of IPMI based fencing can also exist due to other reasons also.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">A failure to fence the failed node will cause cluster to be marked UNCLEAN.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">To get over it, the following command needs to be invoked on the surviving node.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">pcs stonith confirm <failed_node_name> --force</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">This can be automated by hooking a recovery script, when the the Stonith resource ‘Timed Out’ event.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">To be more specific, the Pacemaker Alerts can be used for watch for Stonith timeouts and failures.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">In that script, all that’s essentially to be executed is the aforementioned command.</span><o:p></o:p></p>
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<p class="MsoNormal"><br>
If I get you right here you can disable fencing then in the first place.<br>
Actually quorum-based-watchdog-fencing is the way to do this in a<br>
safe manner. This of course assumes you have a proper source for<br>
quorum in your 2-node-setup with e.g. qdevice or using a shared<br>
disk with sbd (not directly pacemaker quorum here but similar thing<br>
handled inside sbd).<br>
<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Since the alerts are issued from ‘hacluster’ login, sudo permissions for ‘hacluster’ needs to be configured.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thanx.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:windowtext">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:windowtext"> Klaus Wenninger [</span><a href="mailto:kwenning@redhat.com"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif">mailto:kwenning@redhat.com</span></a><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:windowtext">]
<br>
<b>Sent:</b> Monday, July 24, 2017 9:24 PM<br>
<b>To:</b> Kristián Feldsam; Cluster Labs - All topics related to open-source clustering welcomed<br>
<b>Subject:</b> Re: [ClusterLabs] Two nodes cluster issue</span><o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">On 07/24/2017 05:37 PM, Kristián Feldsam wrote:<o:p></o:p></p>
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<p class="MsoNormal">I personally think that power off node by switched pdu is more safe, or not?<o:p></o:p></p>
</blockquote>
<p class="MsoNormal"><br>
True if that is working in you environment. If you can't do a physical setup<br>
where you aren't simultaneously loosing connection to both your node and<br>
the switch-device (or you just want to cover cases where that happens)<br>
you have to come up with something else.<br>
<br>
<br>
<br>
<o:p></o:p></p>
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<p class="MsoNormal"><br>
<span style="font-family:"Baskerville",serif">S pozdravem Kristián Feldsam<br>
Tel.: +420 773 303 353, +421 944 137 535<br>
E-mail.: </span><a href="mailto:support@feldhost.cz"><span style="font-family:"Baskerville",serif">support@feldhost.cz</span></a><span style="font-family:"Baskerville",serif"><br>
<br>
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<br>
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Číslo účtu: 2400330446/2010<br>
BIC: FIOBCZPPXX<br>
IBAN: CZ82 2010 0000 0024 0033 0446</span> <o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal">On 24 Jul 2017, at 17:27, Klaus Wenninger <<a href="mailto:kwenning@redhat.com">kwenning@redhat.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Baskerville",serif">On 07/24/2017 05:15 PM, Tomer Azran wrote:</span><o:p></o:p></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:11.0pt;font-family:"Arial",sans-serif">I still don't understand why the qdevice concept doesn't help on this situation. Since the master node is down, I would expect the quorum to declare
it as dead.</span><o:p></o:p></p>
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<p class="MsoNormal" style="background:white"><span style="font-size:11.0pt;font-family:"Arial",sans-serif">Why doesn't it happens?</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Baskerville",serif"><br>
That is not how quorum works. It just limits the decision-making to the quorate subset of the cluster.<br>
Still the unknown nodes are not sure to be down.<br>
That is why I suggested to have quorum-based watchdog-fencing with sbd.<br>
That would assure that within a certain time all nodes of the non-quorate part<br>
of the cluster are down.<br>
<br>
<br>
<br>
</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-family:"Baskerville",serif"><br>
<br>
<br>
</span><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-family:"Baskerville",serif">On Mon, Jul 24, 2017 at 4:15 PM +0300, "Dmitri Maziuk"<span class="apple-converted-space"> </span><</span><a href="mailto:dmitri.maziuk@gmail.com" target="_blank"><span style="font-family:"Baskerville",serif">dmitri.maziuk@gmail.com</span></a><span style="font-family:"Baskerville",serif">><span class="apple-converted-space"> </span>wrote:</span><o:p></o:p></p>
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<pre>On 2017-07-24 07:51, Tomer Azran wrote:<o:p></o:p></pre>
<pre>> We don't have the ability to use it.<o:p></o:p></pre>
<pre>> Is that the only solution?<o:p></o:p></pre>
<pre> <o:p></o:p></pre>
<pre>No, but I'd recommend thinking about it first. Are you sure you will <o:p></o:p></pre>
<pre>care about your cluster working when your server room is on fire? 'Cause <o:p></o:p></pre>
<pre>unless you have halon suppression, your server room is a complete <o:p></o:p></pre>
<pre>write-off anyway. (Think water from sprinklers hitting rich chunky volts <o:p></o:p></pre>
<pre>in the servers.)<o:p></o:p></pre>
<pre> <o:p></o:p></pre>
<pre>Dima<o:p></o:p></pre>
<pre> <o:p></o:p></pre>
<pre>_______________________________________________<o:p></o:p></pre>
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<p class="MsoNormal"><span style="font-family:"Baskerville",serif"><br>
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<pre> <o:p></o:p></pre>
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<pre style="background:white;font-variant-caps: normal;text-align:start;-webkit-text-stroke-width: 0px;word-spacing:0px"><span style="font-size:12.0pt">-- </span><o:p></o:p></pre>
<pre style="background:white"><span style="font-size:12.0pt">Klaus Wenninger</span><o:p></o:p></pre>
<pre style="background:white"><span style="font-size:12.0pt"> </span><o:p></o:p></pre>
<pre style="background:white"><span style="font-size:12.0pt">Senior Software Engineer, EMEA ENG Openstack Infrastructure</span><o:p></o:p></pre>
<pre style="background:white"><span style="font-size:12.0pt"> </span><o:p></o:p></pre>
<pre style="background:white"><span style="font-size:12.0pt">Red Hat</span><o:p></o:p></pre>
<pre style="background:white"><span style="font-size:12.0pt"> </span><o:p></o:p></pre>
<pre style="background:white"><a href="mailto:kwenning@redhat.com"><span style="font-size:12.0pt">kwenning@redhat.com</span></a><span style="font-size:12.0pt"> </span><o:p></o:p></pre>
<p class="MsoNormal"><span style="font-family:"Baskerville",serif">_______________________________________________<br>
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Getting started:<span class="apple-converted-space"> </span></span><a href="http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf"><span style="font-family:"Baskerville",serif">http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf</span></a><span style="font-family:"Baskerville",serif"><br>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><br>
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<o:p></o:p></p>
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<pre><o:p> </o:p></pre>
<pre>Project Home: <a href="http://www.clusterlabs.org">http://www.clusterlabs.org</a><o:p></o:p></pre>
<pre>Getting started: <a href="http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf">http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf</a><o:p></o:p></pre>
<pre>Bugs: <a href="http://bugs.clusterlabs.org">http://bugs.clusterlabs.org</a><o:p></o:p></pre>
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