<html><body><p><font size="2">Thanks Gerry.<br><br>Hi Reid,<br></font><br><font size="2">The shared storage solution we are using has clustering capabilities of its own built into it and is able to remotely fence off the lost node, all we need to do is run the command to expel/fence the lost node as part of our own custom fencing agent on the surviving node.<br><br>FYI, the shared storage solution I am referring to here is IBM Spectrum Scale.</font><br><font size="2"><br>Thanks,</font><br><br><b><font size="2">Phil Stedman</font></b><br><font size="2">Db2 High Availability Development and Support<br>Email: pmstedma@us.ibm.com</font><br><br><img width="16" height="16" src="cid:1__=8FBB0F26DFFB89448f9e8a93df938690918c8FB@" border="0" alt="Inactive hide details for Gerry R Sommerville---07/30/2020 11:55:48 AM---Seems like we lost Phil in the first reply.... Adding "><font size="2" color="#424282">Gerry R Sommerville---07/30/2020 11:55:48 AM---Seems like we lost Phil in the first reply.... Adding him back.</font><br><br><font size="2" color="#5F5F5F">From: </font><font size="2">Gerry R Sommerville/Markham/IBM</font><br><font size="2" color="#5F5F5F">To: </font><font size="2">nwahl@redhat.com</font><br><font size="2" color="#5F5F5F">Cc: </font><font size="2">developers@clusterlabs.org, Toby Haynes/Toronto/IBM@IBMCA, Alan Y Lee/Toronto/IBM@IBMCA, Philippe M Stedman/Silicon Valley/IBM@IBMUS</font><br><font size="2" color="#5F5F5F">Date: </font><font size="2">07/30/2020 11:55 AM</font><br><font size="2" color="#5F5F5F">Subject: </font><font size="2">Re: [EXTERNAL] Re: [ClusterLabs Developers] How to implement fencing agent with no associated hardware device with Pacemaker?</font><br><hr width="100%" size="2" align="left" noshade style="color:#8091A5; "><br><br><br><font size="2" face="Arial">Seems like we lost Phil in the first reply.... Adding him back.<br> </font><br><b><font color="#7C7C5F">Gerry Sommerville</font></b><br><b><font size="2">Db2 Development, pureScale Domain</font></b><br><b><font size="1" color="#336699">E-mail: </font></b><a href="mailto:gerry@ca.ibm.com"><u><font size="1" color="#555555">gerry@ca.ibm.com</font></u></a><br><font size="2" face="Arial"> </font><br><font size="2" face="Arial"> </font><br><font size="2" face="Arial">----- Original message -----<br>From: Reid Wahl <nwahl@redhat.com><br>To: developers@clusterlabs.org<br>Cc: Toby Haynes <thaynes@ca.ibm.com>, Gerry R Sommerville <gerry@ca.ibm.com>, Alan Y Lee <ykalee@ca.ibm.com><br>Subject: [EXTERNAL] Re: [ClusterLabs Developers] How to implement fencing agent with no associated hardware device with Pacemaker?<br>Date: Wed, Jul 29, 2020 11:42 PM<br> </font><br><font size="2" face="Arial">I didn't see the phrase "how to develop" until after I sent the previous message. What is the reason for needing to develop a custom fencing agent? An already-built one might save you some work.</font><br><font size="2" face="Arial"> </font><br><font size="2" face="Arial">Basically, you need some reliable method to cut off an unhealthy node's access to shared storage, without depending on that node being responsive. So for example, anything that involves logging into the failed node is unreliable.</font><br><font size="2" face="Arial"> </font><br><font size="2" face="Arial">On Wed, Jul 29, 2020 at 8:40 PM Reid Wahl <</font><a href="mailto:nwahl@redhat.com" target="_blank"><u><font size="2" color="#0000FF" face="Arial">nwahl@redhat.com</font></u></a><font size="2" face="Arial">> wrote:</font><ul><font size="2" face="Arial">If you have a hardware **watchdog timer**, then sbd is a good option. With shared storage, you can also implement fence_sbd.</font><br><font size="2" face="Arial"> </font><br><font size="2" face="Arial">KVM virtual machines also offer an emulated hardware watchdog. I'm not sure whether that would fit your criteria or not -- it depends on whether you're only excluding a management interface like an iLO/IMM, or whether you're also excluding a watchdog timer.</font><br><font size="2" face="Arial"> </font><br><font size="2" face="Arial">If you can't use sbd or conventional power fencing (e.g., fence_ipmilan), then you may be able to use fence_scsi or fence_mpath since you have shared storage.</font><br><font size="2" face="Arial"> </font><br><font size="2" face="Arial">What hardware or virtualization platform are you running on, and is there a particular reason you don't want to associate fencing with a hardware device?</font><br><font size="2" face="Arial"> </font><br><font size="2" face="Arial">On Wed, Jul 29, 2020 at 8:34 PM Philippe M Stedman <</font><a href="mailto:pmstedma@us.ibm.com" target="_blank"><u><font size="2" color="#0000FF" face="Arial">pmstedma@us.ibm.com</font></u></a><font size="2" face="Arial">> wrote:</font><br><font size="2" face="Arial">Hi ClusterLabs developers,<br><br>I am looking into how to develop a fencing agent for Pacemaker that is not associated to any underlying hardware device. In our case we have two servers (we will expand to more in the future) which have access to shared storage. When one of the two nodes fails, we expect the surviving node to invoke our user-defined fencing agent and run a series of commands which will "expel" the lost host from accessing shared storage.<br><br>Do you have any advice on how to go about implementing such a solution? All the examples I can find online revolve around using some sort of underlying hardware device to implement fencing.<br><br>Help is greatly appreciated.<br><br>Thanks,<br></font><b><font size="2" face="Arial"><br>Phil Stedman</font></b><font size="2" face="Arial"><br>Db2 High Availability Development and Support<br>Email: </font><a href="mailto:pmstedma@us.ibm.com" target="_blank"><u><font size="2" color="#0000FF" face="Arial">pmstedma@us.ibm.com</font></u></a><br><font size="2" face="Arial">_______________________________________________<br>Manage your subscription:</font><u><font size="2" color="#0000FF" face="Arial"><br></font></u><a href="https://lists.clusterlabs.org/mailman/listinfo/developers" target="_blank"><u><font size="2" color="#0000FF" face="Arial">https://lists.clusterlabs.org/mailman/listinfo/developers</font></u></a><font size="2" face="Arial"><br><br>ClusterLabs home: </font><a href="https://www.clusterlabs.org/" target="_blank"><u><font size="2" color="#0000FF" face="Arial">https://www.clusterlabs.org/</font></u></a><br><font size="2" face="Arial"><br><br>-- </font><br><font size="2" face="Arial">Regards,<br> </font><br><font size="2" face="Arial">Reid Wahl, RHCA</font><br><font size="2" face="Arial">Software Maintenance Engineer, Red Hat</font><br><font size="2" face="Arial">CEE - Platform Support Delivery - ClusterHA</font></ul><font size="2" face="Arial"><br><br>-- </font><br><font size="2" face="Arial">Regards,<br> </font><br><font size="2" face="Arial">Reid Wahl, RHCA</font><br><font size="2" face="Arial">Software Maintenance Engineer, Red Hat</font><br><font size="2" face="Arial">CEE - Platform Support Delivery - ClusterHA</font><br><font size="2" face="Arial"> </font><br><br><BR>
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