On Tue, 2017-08-08 at 17:40 +0530, Sriram wrote: > Hi Ulrich, > > > Please see inline. > > On Tue, Aug 8, 2017 at 2:01 PM, Ulrich Windl > <ulrich.wi...@rz.uni-regensburg.de> wrote: > >>> Sriram <sriram...@gmail.com> schrieb am 08.08.2017 um > 09:30 in Nachricht > <CAMvdjurcQc6t=ZfGr=cRL25Xq0Je9h9F_TvZXyxVAn3n > +dv...@mail.gmail.com>: > > Hi Ken & Jan, > > > > In the cluster we have, there is only one resource running. > Its a OPT-IN > > cluster with resource-stickiness set to INFINITY. > > > > Just to clarify my question, lets take a scenario where > there are four > > nodes N1, N2, N3, N4 > > a. N1 comes up first, starts the cluster. > > The cluster will start once it has a quorum. > > > b. N1 Checks that there is no resource running, so it will > add the > > resource(R) with the some location constraint(lets say score > 100) > > c. So Resource(R) runs in N1 now. > > d. N2 comes up next, checks that resource(R) is already > running in N1, so > > it will update the location constraint(lets say score 200) > > e. N3 comes up next, checks that resource(R) is already > running in N1, so > > it will update the location constraint(lets say score 300) > > See my remark on quorum above. > > Yes you are right, I forgot to mention it. > > > > f. N4 comes up next, checks that resource(R) is already > running in N1, so > > it will update the location constraint(lets say score 400) > > g. For the some reason, if N1 goes down, resource(R) shifts > to N4(as its > > score is higher than anyone). > > > > In this case is it possible to notify the nodes N2, N3 that > newly elected > > active node is N4 ? > > What type of notification, and what would the node do with it? > Any node in the cluster always has up to date configuration > information. So it knows the status of the other nodes also. > > > 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. ?
Ah, I misunderstood your situation, I thought you had a cloned resource. For that, the alerts feature (available in Pacemaker 1.1.15 and later) might be useful: http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-single/Pacemaker_Explained/index.html#idm139900098676896 > > > Regards, > Sriram. > > > > > I went through clone notifications and master-slave, Iooks > like it either > > requires identical resources(Anonymous) or Unique or > Stateful resources to > > be running > > in all the nodes of the cluster, where as in our case there > is only > > resource running in the whole cluster. > > 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. > > Regards, > Ulrich > > > > > Regards, > > Sriram. > > > > > > > > > > On Mon, Aug 7, 2017 at 11:28 AM, Sriram > <sriram...@gmail.com> wrote: > > > >> > >> Thanks Ken, Jan. Will look into the clone notifications. > >> > >> Regards, > >> Sriram. > >> > >> On Sat, Aug 5, 2017 at 1:25 AM, Ken Gaillot > <kgail...@redhat.com> wrote: > >> > >>> On Thu, 2017-08-03 at 12:31 +0530, Sriram wrote: > >>> > > >>> > Hi Team, > >>> > > >>> > > >>> > We have a four node cluster (1 active : 3 standby) in > our lab for a > >>> > particular service. If the active node goes down, one of > the three > >>> > standby node becomes active. Now there will be (1 > active : 2 > >>> > standby : 1 offline). > >>> > > >>> > > >>> > Is there any way where this newly elected node sends > notification to > >>> > the remaining 2 standby nodes about its new status ? > >>> > >>> Hi Sriram, > >>> > >>> This depends on how your service is configured in the > cluster. > >>> > >>> If you have a clone or master/slave resource, then clone > notifications > >>> is probably what you want (not alerts, which is the path > you were going > >>> down -- alerts are designed to e.g. email a system > administrator after > >>> an important event). > >>> > >>> For details about clone notifications, see: > >>> > >>> > http://clusterlabs.org/doc/en-US/Pacemaker/1.1-pcs/html-sing > >>> > le/Pacemaker_Explained/index.html#_clone_resource_agent_requirements > >>> > >>> The RA must support the "notify" action, which will be > called when a > >>> clone instance is started or stopped. See the similar > section later for > >>> master/slave resources for additional information. See the > mysql or > >>> pgsql resource agents for examples of notify > implementations. > >>> > >>> > I was exploring "notification agent" and "notification > recipient" > >>> > features, but that doesn't seem to > work. /etc/sysconfig/notify.sh > >>> > doesn't get invoked even in the newly elected active > node. > >>> > >>> Yep, that's something different altogether -- it's only > enabled on RHEL > >>> systems, and solely for backward compatibility with an > early > >>> implementation of the alerts interface. The new alerts > interface is more > >>> flexible, but it's not designed to send information > between cluster > >>> nodes -- it's designed to send information to something > external to the > >>> cluster, such as a human, or an SNMP server, or a > monitoring system. > >>> > >>> > >>> > Cluster Properties: > >>> > cluster-infrastructure: corosync > >>> > dc-version: 1.1.17-e2e6cdce80 > >>> > default-action-timeout: 240 > >>> > have-watchdog: false > >>> > no-quorum-policy: ignore > >>> > notification-agent: /etc/sysconfig/notify.sh > >>> > notification-recipient: /var/log/notify.log > >>> > placement-strategy: balanced > >>> > stonith-enabled: false > >>> > symmetric-cluster: false > >>> > > >>> > > >>> > > >>> > > >>> > I m using the following versions of pacemaker and > corosync. > >>> > > >>> > > >>> > /usr/sbin # ./pacemakerd --version > >>> > Pacemaker 1.1.17 > >>> > Written by Andrew Beekhof > >>> > /usr/sbin # ./corosync -v > >>> > Corosync Cluster Engine, version '2.3.5' > >>> > Copyright (c) 2006-2009 Red Hat, Inc. > >>> > > >>> > > >>> > Can you please suggest if I m doing anything wrong or if > there any > >>> > other mechanisms to achieve this ? > >>> > > >>> > > >>> > Regards, > >>> > Sriram. -- Ken Gaillot <kgail...@redhat.com> _______________________________________________ Users mailing list: Users@clusterlabs.org http://lists.clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org