<div dir="ltr">Hi Ulrich,<div><br></div><div>Please see inline.<br><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Aug 8, 2017 at 2:01 PM, Ulrich Windl <span dir="ltr"><<a href="mailto:Ulrich.Windl@rz.uni-regensburg.de" target="_blank">Ulrich.Windl@rz.uni-regensburg.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">>>> Sriram <<a href="mailto:sriram.ec@gmail.com">sriram.ec@gmail.com</a>> schrieb am <a href="tel:08.08.2017" value="+498082017">08.08.2017</a> um 09:30 in Nachricht<br>
<CAMvdjurcQc6t=ZfGr=<a href="mailto:cRL25Xq0Je9h9F_TvZXyxVAn3n%2BDvcgw@mail.gmail.com">cRL25Xq0Je<wbr>9h9F_TvZXyxVAn3n+Dvcgw@mail.<wbr>gmail.com</a>>:<br>
<span class="">> Hi Ken & Jan,<br>
><br>
> In the cluster we have, there is only one resource running. Its a OPT-IN<br>
> cluster with resource-stickiness set to INFINITY.<br>
><br>
> Just to clarify my question, lets take a scenario where there are four<br>
> nodes N1, N2, N3, N4<br>
> a. N1 comes up first, starts the cluster.<br>
<br>
</span>The cluster will start once it has a quorum.<br>
<span class=""><br>
> b. N1 Checks that there is no resource running, so it will add the<br>
> resource(R) with the some location constraint(lets say score 100)<br>
> c. So Resource(R) runs in N1 now.<br>
> d. N2 comes up next, checks that resource(R) is already running in N1, so<br>
> it will update the location constraint(lets say score 200)<br>
> e. N3 comes up next, checks that resource(R) is already running in N1, so<br>
> it will update the location constraint(lets say score 300)<br>
<br>
</span>See my remark on quorum above.<br>
<span class=""><br></span></blockquote><div>Yes you are right, I forgot to mention it. </div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">
> f. N4 comes up next, checks that resource(R) is already running in N1, so<br>
> it will update the location constraint(lets say score 400)<br>
> g. For the some reason, if N1 goes down, resource(R) shifts to N4(as its<br>
> score is higher than anyone).<br>
><br>
> In this case is it possible to notify the nodes N2, N3 that newly elected<br>
> active node is N4 ?<br>
<br>
</span>What type of notification, and what would the node do with it?<br>
Any node in the cluster always has up to date configuration information. So it knows the status of the other nodes also.<br></blockquote><div><br></div><div>I agree that the node always has upto date configuration information, but an application or a thread needs to poll for that information. Is there any way, where the notifications are received through some action function in RA. ?</div><div><br></div><div>Regards,</div><div>Sriram. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<span class=""><br>
><br>
> I went through clone notifications and master-slave, Iooks like it either<br>
> requires identical resources(Anonymous) or Unique or Stateful resources to<br>
> be running<br>
> in all the nodes of the cluster, where as in our case there is only<br>
> resource running in the whole cluster.<br>
<br>
</span>Maybe the main reason for not having notifications is that if a node fails hard, it won't be able to send out much status information to the other nodes.<br>
<br>
Regards,<br>
Ulrich<br>
<div class="HOEnZb"><div class="h5"><br>
><br>
> Regards,<br>
> Sriram.<br>
><br>
><br>
><br>
><br>
> On Mon, Aug 7, 2017 at 11:28 AM, Sriram <<a href="mailto:sriram.ec@gmail.com">sriram.ec@gmail.com</a>> wrote:<br>
><br>
>><br>
>> Thanks Ken, Jan. Will look into the clone notifications.<br>
>><br>
>> Regards,<br>
>> Sriram.<br>
>><br>
>> On Sat, Aug 5, 2017 at 1:25 AM, Ken Gaillot <<a href="mailto:kgaillot@redhat.com">kgaillot@redhat.com</a>> wrote:<br>
>><br>
>>> On Thu, 2017-08-03 at 12:31 +0530, Sriram wrote:<br>
>>> ><br>
>>> > Hi Team,<br>
>>> ><br>
>>> ><br>
>>> > We have a four node cluster (1 active : 3 standby) in our lab for a<br>
>>> > particular service. If the active node goes down, one of the three<br>
>>> > standby node becomes active. Now there will be (1 active : 2<br>
>>> > standby : 1 offline).<br>
>>> ><br>
>>> ><br>
>>> > Is there any way where this newly elected node sends notification to<br>
>>> > the remaining 2 standby nodes about its new status ?<br>
>>><br>
>>> Hi Sriram,<br>
>>><br>
>>> This depends on how your service is configured in the cluster.<br>
>>><br>
>>> If you have a clone or master/slave resource, then clone notifications<br>
>>> is probably what you want (not alerts, which is the path you were going<br>
>>> down -- alerts are designed to e.g. email a system administrator after<br>
>>> an important event).<br>
>>><br>
>>> For details about clone notifications, see:<br>
>>><br>
>>> <a href="http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-sing" rel="noreferrer" target="_blank">http://clusterlabs.org/doc/en-<wbr>US/Pacemaker/1.1-pcs/html-sing</a><br>
>>> le/Pacemaker_Explained/index.<wbr>html#_clone_resource_agent_<wbr>requirements<br>
>>><br>
>>> The RA must support the "notify" action, which will be called when a<br>
>>> clone instance is started or stopped. See the similar section later for<br>
>>> master/slave resources for additional information. See the mysql or<br>
>>> pgsql resource agents for examples of notify implementations.<br>
>>><br>
>>> > I was exploring "notification agent" and "notification recipient"<br>
>>> > features, but that doesn't seem to work. /etc/sysconfig/notify.sh<br>
>>> > doesn't get invoked even in the newly elected active node.<br>
>>><br>
>>> Yep, that's something different altogether -- it's only enabled on RHEL<br>
>>> systems, and solely for backward compatibility with an early<br>
>>> implementation of the alerts interface. The new alerts interface is more<br>
>>> flexible, but it's not designed to send information between cluster<br>
>>> nodes -- it's designed to send information to something external to the<br>
>>> cluster, such as a human, or an SNMP server, or a monitoring system.<br>
>>><br>
>>><br>
>>> > Cluster Properties:<br>
>>> > cluster-infrastructure: corosync<br>
>>> > dc-version: 1.1.17-e2e6cdce80<br>
>>> > default-action-timeout: 240<br>
>>> > have-watchdog: false<br>
>>> > no-quorum-policy: ignore<br>
>>> > notification-agent: /etc/sysconfig/notify.sh<br>
>>> > notification-recipient: /var/log/notify.log<br>
>>> > placement-strategy: balanced<br>
>>> > stonith-enabled: false<br>
>>> > symmetric-cluster: false<br>
>>> ><br>
>>> ><br>
>>> ><br>
>>> ><br>
>>> > I m using the following versions of pacemaker and corosync.<br>
>>> ><br>
>>> ><br>
>>> > /usr/sbin # ./pacemakerd --version<br>
>>> > Pacemaker 1.1.17<br>
>>> > Written by Andrew Beekhof<br>
>>> > /usr/sbin # ./corosync -v<br>
>>> > Corosync Cluster Engine, version '2.3.5'<br>
>>> > Copyright (c) 2006-2009 Red Hat, Inc.<br>
>>> ><br>
>>> ><br>
>>> > Can you please suggest if I m doing anything wrong or if there any<br>
>>> > other mechanisms to achieve this ?<br>
>>> ><br>
>>> ><br>
>>> > Regards,<br>
>>> > Sriram.<br>
>>> ><br>
>>> ><br>
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>>> --<br>
>>> Ken Gaillot <<a href="mailto:kgaillot@redhat.com">kgaillot@redhat.com</a>><br>
>>><br>
>>><br>
>>><br>
>>><br>
>>><br>
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>>><br>
>><br>
>><br>
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</div></div></blockquote></div><br></div></div></div>