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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>My understanding is that SBD will need a shared storage between clustered nodes.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>And that, SBD will need at least 3 nodes in a cluster, if using w/o shared storage.<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Therefore, for systems which do NOT use shared storage between 1+1 HA clustered nodes, SBD may NOT be an option.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Correct me, if I am wrong.<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>For cluster systems using the likes of iDRAC/IMM2 fencing agents, which have redundant but shared power supply units with the nodes, the normal fencing mechanisms should work for all resiliency scenarios, but for IMM2/iDRAC are being NOT reachable for whatsoever reasons. And, to bail out of those situations in the absence of SBD, I believe using used-defined failover hooks (via scripts) into Pacemaker Alerts, with sudo permissions for ‘hacluster’, should help.<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thanx.<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><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 [mailto:kwenning@redhat.com] <br><b>Sent:</b> Monday, July 24, 2017 11:31 PM<br><b>To:</b> Cluster Labs - All topics related to open-source clustering welcomed; Prasad, Shashank<br><b>Subject:</b> Re: [ClusterLabs] Two nodes cluster issue<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>On 07/24/2017 07:32 PM, Prasad, Shashank wrote:<o:p></o:p></p></div><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'>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></blockquote><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><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><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><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 [<a href="mailto:kwenning@redhat.com">mailto:kwenning@redhat.com</a>] <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></div></div><p class=MsoNormal> <o:p></o:p></p><div><p class=MsoNormal>On 07/24/2017 05:37 PM, Kristián Feldsam wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><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><div><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.: <a href="mailto:support@feldhost.cz">support@feldhost.cz</a><br><br><a href="http://www.feldhost.cz">www.feldhost.cz</a> -<span class=apple-converted-space> </span><b>Feld</b>Host</span>™<span class=apple-converted-space><span style='font-family:"Baskerville","serif"'> </span></span><span style='font-family:"Baskerville","serif"'>– profesionální hostingové a serverové služby za adekvátní ceny.<br><br>FELDSAM s.r.o.<br>V rohu 434/3<br>Praha 4 – Libuš, PSČ 142 00<br>IČ: 290 60 958, DIČ: CZ290 60 958<br>C 200350 vedená u Městského soudu v Praze<br><br>Banka: Fio banka a.s.<br>Číslo účtu: 2400330446/2010<br>BIC: FIOBCZPPXX<br>IBAN: CZ82 2010 0000 0024 0033 0446</span> <o:p></o:p></p></div><p class=MsoNormal> <o:p></o:p></p><div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><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></div><p class=MsoNormal> <o:p></o:p></p><div><div><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></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt;font-variant-caps:
normal;orphans: auto;text-align:start;widows:
auto;-webkit-text-size-adjust:
auto;-webkit-text-stroke-width:
0px;background-color:rgb(255,
255,
255);word-spacing:0px'><div><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></div><div><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></div></blockquote><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><div><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><<a href="mailto:dmitri.maziuk@gmail.com" target="_blank">dmitri.maziuk@gmail.com</a>><span class=apple-converted-space> </span>wrote:</span><o:p></o:p></p><div><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><pre>Users mailing list: <a href="mailto:Users@clusterlabs.org">Users@clusterlabs.org</a><o:p></o:p></pre><pre><a href="http://lists.clusterlabs.org/mailman/listinfo/users">http://lists.clusterlabs.org/mailman/listinfo/users</a><o:p></o:p></pre><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></div></div><p class=MsoNormal><span style='font-family:"Baskerville","serif"'><br><br><br><br></span><o:p></o:p></p><pre>_______________________________________________<o:p></o:p></pre><pre>Users mailing list: <a href="mailto:Users@clusterlabs.org">Users@clusterlabs.org</a><o:p></o:p></pre><pre><a href="http://lists.clusterlabs.org/mailman/listinfo/users">http://lists.clusterlabs.org/mailman/listinfo/users</a><o:p></o:p></pre><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><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;font-variant-caps:
normal;text-align:start;-webkit-text-stroke-width:
0px;background-color:rgb(255,
255,
255);word-spacing:0px'><span style='font-family:"Baskerville","serif"'> </span><o:p></o:p></p><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'><span style='font-size:12.0pt'><a href="mailto:kwenning@redhat.com">kwenning@redhat.com</a> </span><o:p></o:p></pre><p class=MsoNormal><span style='font-family:"Baskerville","serif"'>_______________________________________________<br>Users mailing list:<span class=apple-converted-space> </span></span><a href="mailto:Users@clusterlabs.org"><span style='font-family:"Baskerville","serif";background:white'>Users@clusterlabs.org</span></a><span style='font-family:"Baskerville","serif"'><br></span><a href="http://lists.clusterlabs.org/mailman/listinfo/users"><span style='font-family:"Baskerville","serif"'>http://lists.clusterlabs.org/mailman/listinfo/users</span></a><span style='font-family:"Baskerville","serif"'><br><br>Project Home:<span class=apple-converted-space> </span></span><a href="http://www.clusterlabs.org/"><span style='font-family:"Baskerville","serif";background:white'>http://www.clusterlabs.org</span></a><span style='font-family:"Baskerville","serif"'><br>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>Bugs:<span class=apple-converted-space> </span></span><a href="http://bugs.clusterlabs.org/"><span style='font-family:"Baskerville","serif";background:white'>http://bugs.clusterlabs.org</span></a><o:p></o:p></p></div></blockquote></div><p class=MsoNormal> <o:p></o:p></p></div><p class=MsoNormal><br><br><br><o:p></o:p></p><pre>_______________________________________________<o:p></o:p></pre><pre>Users mailing list: <a href="mailto:Users@clusterlabs.org">Users@clusterlabs.org</a><o:p></o:p></pre><pre><a href="http://lists.clusterlabs.org/mailman/listinfo/users">http://lists.clusterlabs.org/mailman/listinfo/users</a><o:p></o:p></pre><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><pre> <o:p></o:p></pre></div></div></body></html>